RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4

RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4

These Solutions are part of RD Sharma Class 10 Solutions. Here we have given RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4

Other Exercises

Question 1.
A plot is in the form of a rectangle ABCD having semi-circle on BC as shown in the figure. If AB = 60 m and BC = 28 m, find the area of the plot.
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 1
Solution:
Plot is formed of a rectangle ABCD and one semicircle on BC as diameter
∴  AB (l) = 60 m,
BC (b) = 28 m
∴ Radius of semicircle (r) = \(\frac { 1 }{ 2 }\) BC
= \(\frac { 1 }{ 2 }\) x 28 = 14m
Area of plot = area of rectangle ABCD + area of semicircle
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 2
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 3

Question 2.
A play ground has the shape of a rectangle, with two semi-circles on its smaller sides as diameters, added to its outside. If the sides of the rectangle are 36 m and 24.5 m, find the area of the playground. (Take π = 22/7).
Solution:
Length of rectangle (l) = 36 m 49
and width (b) = 24.5 =  \(\frac { 49 }{ 2 }\) m
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 4
Question 3.
Find the area of the circle in which a square of area 64 cm2 is inscribed. (Use π = 3.14)
Solution:
Area of square = 64 cm²
∴  Side of square = \(\sqrt { Area } \)  = \(\sqrt { 64 } \)  = 8 cm
∵ The square in inscribed in the circle
∴  Radius of the circle will be = \(\frac { 1 }{ 2 }\) diagonal of
the square (r)=\(\frac { 1 }{ 2 }\) x \(\sqrt { 2 } \)a = \(\frac { 1 }{ 2 }\) x \(\sqrt { 2 } \) x 8 cm = 4\(\sqrt { 2 } \)
∴ Area of the circle = πr²
= 3.14 x (4\(\frac { 1 }{ 2 }\) x \(\sqrt { 2 } \) x 8 cm = 4\(\sqrt { 2 } \))² cm²
= 3.14 x 32 = 100.48 cm²

Question 4.
A rectangular piece is 20 m long and 15 m wide. From its four corners, quadrants of radii 3.5 m have been cut. Find the area of the remaining part.
Solution:
Length of rectangular piece (l) = 20 m
and width (b) = 15m
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 5
Radius of each quadrant (r) = 3.5 m = \(\frac { 7 }{ 2 }\) m
Now area of the rectangle = l x b = 20 x 15 = 300 m²
and area of 4 quadrants = 4 x \(\frac { 1 }{ 4 }\) πr²
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 6

Question 5.
In the figure, PQRS is a square of side 4 cm. Find the area of the shaded square.

RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 7
Solution:
Side of the square PQRS (a) = 4 cm
∴ Area of total square = a² = 4×4=16 cm²
Radius of each of the four quadrants at the corners = 1 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 8

Question 6.
Four cows are tethered at four corners of a square plot of side 50 m, so that they just cannot reach one another. What area will be left ungrazed ? (See figure)
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 9
Solution:
side of square (a) = 50 m
∴ Area of the square field = a² = (50)² m² = 2500 m²
Radius of each quadrant (r) = \(\frac { 50 }{ 2 }\) = 25 m
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 10

Question 7.
A cow is tied with a rope of length 14 m at the corner of a rectangular field of dimensions 20 m x 16 m, find the area of the field in which the cow can graze. [NCERT Exemplar]
Solution:
Let ABCD be a rectangular field of dimensions 20 m x 16 m.
Suppose, a cow is tied at a point A.  Let length of rope AE = 14m =r (say).
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 11

Question 8.
A calf is teid with a rope of length 6 m at the corner of a square grassy lawn of side 20 m. If the length of the rope is increased by 5.5 m, find the increase in area of the grassy lawn in which the calf can graze. [NCERT Exemplar]
Solution:
Let the calf be tied at the corner A of the square lawn.
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 12
Then, the increase in area = Difference of the two sectors of central angle 90° each and radii 11.5 m (6 m + 5.5 m) and 6 m, which is the shaded region in the figure.
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 13

Question 9.
A square water tank has its side equal to 40 m. There are four semi-circular grassy plots all round it. Find the cost of turfing the plot at ?1.25 per square metre (Take π = 3.14).
Solution:
Side of square tank (a) = 40 m
Radius of each semicircular grassy plots = \(\frac { 40 }{ 2 }\) = 20
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 14

Question 10.
A rectangular park is 100 m by 50 m. It is surrounded by semi-circular flower beds all round. Find the cost of levelling the semi-circular flower beds at 60 paise per square metre. (Use π = 3.14).
Solution:
Length of rectangular park (l) = 100 m
and width (b) = 50 m
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 15
Radius of each semicircular beds along the
lengths side (R) = \(\frac { 100 }{ 2 }\)  = 50 m
and radius of each semicircular beds along
the width side (r) = \(\frac { 50 }{ 2 }\) = 25 m
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 16

Question 11.
The inside perimeter of a running track (shown in the figure) is 400 m. The length of each of the straight portion is 90 m and the ends are semi-circles. If the track is everywhere 14 m wide, find the area of the track. Also find the length of the outer running track.
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 17
Solution:
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 18
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 19

Question 12.
 Find the area of the figure, in square cm, correct to one place of decimal. (Take π = 22/7).

RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 20
Solution:
Join AD
ABCD is a square whose each side = 10 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 21
Area of square = a² = (10)² = 100 cm²
Area of half semicircle whose radius is \(\frac { 10 }{ 2 }\) = 5
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 22
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 23

Question 13.
In the figure, from a rectangular region ABCD with AB = 20 cm, a right triangle AED with AE = 9 cm and DE = 12 cm, is cut off. On the other end, taking BC as diameter, a semicircle is added on outside the region. Find the area of the shaded region. (Use π = 22/7). [CBSE 2014]
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 24
Solution:
AB = 20 cm, AE = 9 cm, DE = 12 cm
∠AED = 90°
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 25
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 26

Question 14.
From each of the two opposite corners of a square of side 8 cm, a quadrant of a cirlce of radius 1.4 cm is cut. Another circle of diameter 4.2 cm is also cut from the centre as shown in the figure. Find the area of the remaining (shaded) portion of the square. (Use π = 22/7). [CBSE 2010]

RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 27
Solution:
Side of a square ABCD = 8 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 28
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 29

Question 15.
In the figure, ABCD is a rectangle with AB = 14 cm and BC = 7 cm. Taking DC, BC and AD as diameters, three semi¬circles are drawn as shown in the figure. Find the area of the shaded region.

RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 30
Solution:
In the figure, ABCD is a rectangle AB = 14 cm abd BC = 7 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 31
Two semicircles are draw on AD and BC as diameter and thid semicircle is drawn on Cd as diameter
Now area of rectangle ABCD = l x b = 14 x 7 = 98 cm²
Area of two semicircles on AD and BC
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 32

Question 16.
In the figure, ABCD is a rectangle, having AB = 20 cm and BC = 14 cm. Two sectors of 180° have been cut off. Calculate :
(i) the area of the shaded region.
(ii) the length of the boundary of the shaded region.
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 33
Solution:
ABCD is a rectangle whose Length AB = 20 cm
and width BC = 14 cm
∴ Area of the rectangle = l x b = 20 x 14 = 280 cm²
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 34

Question 17.
In the figure, the square ABCD is divided into five equal parts, all having same area. The central part is circular and the lines AE, GC, BF and HD lie along the diagonals AC and BD of the square. If AB = 22 cm, find :
(i) the circumference of the central part.
(ii) the perimeter of the part ABEF.

RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 35
Solution:
Side of the square ABCD = 22 cm
∴  Area = (side)² = (22)² = 484 cm²
∵ The squre is divided into 5 parts equal in area
∴ Area of each part  = \(\frac { 484 }{ 5 }\) cm²
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 36

Question 18.
In the given figure, Find the area of the shaded region. (Use π = 3.14).  [CBSE 2015]
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 37
Solution:
Side of large square = 14 cm
Radius of each semicircle = \(\frac { 4 }{ 2 }\) = 2 cm
Side of square = 4 cm
Area of square =  4 x 4=16 cm²
∴ Area of semicircles = 4 x \(\frac { 1 }{ 2 }\) πr²
= 2 x 3.14 x 2 x 2
= 8 x 3.14
= 25.12 cm²
∴ Area of shaded region = Area of large square – Area of central portion
= (14)2-(16+ 25.12) cm²
= 196-41.12 cm²
= 154.88 .cm²

Question 19.
In the Figure, OACB is a quadrant of a circle with centre O and radius 3.5 cm. If OD = 2 cm, find the area of the
(i) quadrant OACB
(ii) shaded region.

RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 38
Solution:
Radius of outer quadrant (R) = 3.5 cm
and radius of inner quadrant = 2 cm
∴  Area of shaded portion
= Area of outer quadrant – area of inner quadrant
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 39
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 40

Question 20.
In the figure, a square OABC is inscribed in a quadrant OPBQ of a circle. If OA = 21 cm, find the area of the shaded region.[CBSE 2013]
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 41
Solution:
In the figure, OPQ is a quadrant in which
OABC is a square OA = 21 cm
Join OB,
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 42
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 43

Question 21.
In the figure, OABC is a square of side 7 cm. If OAPC is a quadrant of a cirice with centre O, then find the area of the shaded region. (Use π = 22/7) [CBSE 2012]
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 44
Solution:
In square OABC, whose side is 7 cm, OAPC
is a quadrant
Area of square = (side)²
= (7)² = 49 cm²
and radius of quadrant = 7 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 45

Question 22.
In the figure, OE = 20 cm. In sector OSFT, square OEFG is inscribed. Find the area of the shaded region.
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 46
Solution:
In the figure OSFT is a quadrant and OEFG
is a square inscribed in it
The side of the square is OE = 20 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 47
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 48

Question 23.
Find the area of the shaded region in the figure, if AC = 24 cm, BC = 10 cm and O is the centre of the circle. (Use π = 3.14)
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 49
Solution:
In right AABC
AB²=AC² + BC² (Pythagoras Theorem)
= (24)²+ (10)²
= 576 + 100 = 676
= (26)²
∴ AB = 26 cm
∴ Diameter of circle = 26 cm
and radius (r)= \(\frac { 26 }{ 2 }\) = 13 cm
Now area of shaded portion
= Area of semicircle – area of right triangle ABC
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 50

Question 24.
A circle is inscribed in an equilateral triangle ABC is side 12 cm, touching its sides (see figure). Find the radius of the inscribed circle and the area of the shaded part.
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 51
Solution:
Each side of the equilateral triangle ABC (a) = 12 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 52

Question 25.
In the figure, an equilateral triangle ABC of side 6 cm has been inscribed in a circle. Find the area of the shaded region. (Take π = 3.14)
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 53
Solution:
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 54

Question 26.
A circular field has a perimeter of 650 m. A square plot having its vertices on the circumference of the field is marked in the field. Calculate the area of the square plot.
Solution:
Perimeter of the circular field = 650 m
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 55

Question 27.
Find the area of a shaded region in the figure, where a circular arc of radius 7 cm has been drawn with vertex A of an equilateral triangle ABC of side 14 cm as centre, (use π = 22/7 and \(\sqrt { 3 } \)  = 1.73) [CBSE 2015]
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 56
Solution:
Radius of circular arc (r) = 7 cm
and side of equilateral AABC (a) = 14 cm and each angle = 60°
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 57
Area of shaded region
=Area of circle + Area of equilateral triangle – 2 area of sector EAF
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 58

Question 28.
A regular hexagon is inscribed in a circle. If the area of hexagon is 24\(\sqrt { 3 } \) cm², find the area of the circle. (Use π = 3.14) [CBSE 2015]
Solution:
A regular hexagon ABCDEF is inscribed in a circle
Area of hexagon = 24 \(\sqrt { 3 } \) cm²
Let r be the radius of circle
∴ Side of regular hexagon = r
Area of equilateral ΔOAB = \(\frac { \sqrt { 3 } }{ 3 }\) r² sq. units
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 59

Question 29.
ABCDEF is a regular hexagon with centre O (see figure). If the area of triangle OAB is 9 cm², find the area of :
(i) the hexagon and
(ii) the circle in which the hexagon is inscribed.
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 60
Solution:
O is the centre of the regular hexagon ABCDEF and area of the AOAB = 9 cm²
∵ By joining the vertices of the hexagon with O,
(i) We get 6 equal equilateral triangles
∴ Area of hexagon = 9 cm² x 6 = 54 cm²
(ii) Radius of the circle when this hexagon is inscribed in it will be = OB =AB  =r
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 61

Question 30.
Four equal circles, each of radius 5 cm, touch each other as shown in the figure. Find the area included between them. (Take π = 3.14).
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 62
Solution:
Radius of each circle = 5 cm
∵ The four circles touch eachother externally
∴ By joining their centres, we get a square whose side will be 5 + 5 = 10 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 63
Now area of square so formed = a² = (10)² = 100 cm²
and area of 4 quadrants = 4 x \(\frac { 1 }{ 4 }\) πr²= πr²
= 3.14 x (5)2 cm² = 3.14 x 25 cm² = 78.5 cm²
∴  Area of the part included between the circles
= 100 – 78.5
= 21.5 cm²

Question 31.
Four equal circles, each of radius ‘a’ touch each other. Show that the area between them is \(\frac { 6 }{ 7 }\)a² . (Take π = \(\frac { 22 }{ 7 }\)
Solution:
Four circles each of radius ‘a’ touch each other at A, B, C and D respectively.
Their centes are P, Q, R and S respectively
By joining PQ, QR, RS, SD
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 64
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 65

Question 32.
A child makes a poster on a chart paper drawing a square ABCD of side 14 cm. She draws four circles with centre A, B, C and D in which she suggests different ways to save energy. The circles are drawn in such a way that each circle touches externally two of the three remaining circles in the given figure. In the shaded region she write a message ‘Save Energy’. Find the perimeter and area of the shaded region. (Use π = 22/7) [CBSE 2015]
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 66
Solution:
Radius of circular arc (r) = 7 cm
Side of square ABCD (a) = 14 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 67
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 68

Question 33.
The diameter of a coin is 1 cm (see figure). If four such coins be placed on a table so that the rim of each touches that of the other two, find the area of the shaded region (Take π = 3.1416).

RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 69
Solution:
Diameter of each coin = 1 cm
∴ Radius (r) = \(\frac { 1 }{ 2 }\) cm = 0.5 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 70
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 71

Question 34.
Two circular pieces of equal radii and maximum area, touching each other are cut out from a rectangular card board of dimensions 14 cm x 7 cm. Find the area of the remaining card board. (Use π = 22/7) [CBSE 2013]
Solution:
Length of rectangle = 14 cm
and breadth = 7 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 72

Question 35.
In the figure, AB and CD are two diameters of a circle perpendicular to each other and OD is the diameter of the smaller circle. If OA = 7 cm, find the area of the shaded region.
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 73
Solution:
Radius of larger circle (R) = 7 cm
and radius of smaller circle (r) =\(\frac { 7 }{ 2 }\) cm
Area of shaded portion = Area of larger circle – area of smaller circle
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 74

Question 36.
In the figure, PSR, RTQ and PAQ are three semi-circles of diameters 10 cm, 3 cm and 7 cm respectively. Find the perimeter of the shaded region. [CBSE 2014]
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 75
Solution:
Radius of larger semicircle (r1) =\(\frac { 10 }{ 2 }\) = 5 cm
Radius of large semicircle = (r2) = \(\frac { 7 }{ 2 }\) cm
Radius of small semicircle (r3) = \(\frac { 3 }{ 2 }\) cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 76

Question 37.
In the figure, two circles with centres A and B touch each other at the point C. If AC = 8 cm and AB = 3 cm, find the area of the shaded region.
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 77
Solution:
In the figure, two circles with centres A and B touch each-other internally at C
AC = 8 cm and AB = 3 cm
∴  BC = 8 – 3 = 5 cm
∴  Radius of bigger circle (R) = 8 cm
and of smaller circle (r) = 5 cm
∴  Area of shaded portion =Area of bigger circle – area of smaller circle
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 78

Question 38.
In the figure, ABCD is a square of side 2a. Find the ratio between
(i) the circumferences
(ii) the areas of the incircle and the circum- circle of the square.

RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 79
Solution:
A square ABCD is inscribed a circle
The side of the square = 2a
and one circle is inscribed in the square ABCD
Now diameter of the outer circle is AC
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 80
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 81

Question 39.
 In the figure, there are three semicircles, A, B and C having diameter 3 cm each, and another semicircle E having a circle D with diameter 4.5 cm are shown. Calculate :
(i) the area of the shaded region
(ii) the cost of painting the shaded region at the rate of 25 paise per cm², to the nearest rupee.

RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 82
Solution:
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 83
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 84
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 85

Question 40.
 In the figure, ABC is a right-angled triangle, ∠B = 90°, AB = 28 cm and BC = 21 cm. With AC as diameter a semicircle is drawn and with BC as radius a quarter circle is drawn. Find the area of the shaded region correct to two decimal places.
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 86
Solution:
In right ΔABC,
AB = 28 cm, BC = 21 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 87
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 88

Question 41.
In the figure, O is the centre of a circular arc and AOB is a straight line. Find the perimeter and the area of the shaded region correct to one decimal place. (Take π = 3.142)
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 89
Solution:
A semicircle is drawn on the diameter AB
ΔACB is drawn in this semicircle in right ΔACB
AC = 12 cm and BC = 16 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 90
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 91

Question 42.
In the figure, the boundary of the shaded region consists of four semi-circular arcs, the smallest two being equal. If the diameter of the largest is 14 cm and of the smallest is 3.5 cm, find
(i) the length of the boundary,
(ii) the area of the shaded region.
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 92
Solution:
Diameter of the biggest semicircle = 14 cm 14
∴  Radius (R) = \(\frac { 14 }{ 2 }\) = 7 cm
Diameter of the small semicircle = 7 cm 7
∴  Radius (r1) = \(\frac { 7 }{ 2 }\) cm
and diameter of each smaller circles = 3.5 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 93

Question 43.
In the figure, AB = 36 cm and M is mid¬point of AB. Semi-circles are drawn on AB, AM and MB as diameters. A circle with centre C touches all the three circles. Find the area of the shaded region.
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 94
Solution:
In the figure, there are three semicircles one bigger and two smaller There is one small circle also
Now diameter of bigger semicircle = 36 cm
∴   Radius (R) = \(\frac { 36 }{ 2 }\) = 18 cm
and diameter of each smaller semicircle = 18 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 95
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 96

Question 44.
In the figure, ABC is a right angled triangle in which ∠A = 90°, AB = 21 cm and AC = 28 cm. Semi-circles are described on AB, BC and AC as diameters. Find the area of the shaded region.
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 97
Solution:
In the figure, ABC is a right triangle in a semicircle A = 90°, AB = 21 cm and AC  = 28 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 98
Semicircles are drawn on BC and AC as diameters
In right ΔABC
BC² = AB²+AC² (Pythagoras Theorem)
= 21²+ 28²
= 441 + 784= 1225 = (35)²
∴  BC = 35 cm
Now radius of bigger semicircle (R) = \(\frac { 35 }{ 2 }\) cm,
of semicircle at AB = \(\frac { 21 }{ 2 }\) cm and of
semicircle on AC = \(\frac { 28 }{ 2 }\) cm = 14 cm
Now area of shaded portion
= Area of semicircle on AB as diameter + area of semicircle on AC as diameter + area of ΔABC – area of semicircle on BC as diameter
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 99

Question 45.
In the figure, shows the cross-section of railway tunnel. The radius OA of the circular part is 2 m. If ∠AOB = 90°, calculate :
(i) the height of the tunnel
(ii) the perimeter of the cross-section
(iii) the area of the cross-section.

RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 100
Solution:
Radius of the circular part of the tunnel = 2 m
i.e. OA = OB = 2 m
and ∠AOB = 90°
OD ⊥ AB
∴ D in mid-point of AB
∴ In right ΔAOB,
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 101
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 102

Question 46.
In the figure, shows a kite in which BCD is the shape of a quadrant of a circle of radius 42 cm. ABCD is a square and ΔCEF is an isosceles right angled triangle whose equal sides are 6 cm long. Find the area of the shaded region.
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 103
Solution:
ABCD is a square with side = 42 cm
BCD is a quadrant in which ∠BCD = 90° and radius = 42 cm
ΔCEF is an isosceles right triangle in which CE = CF = 6 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 104

Question 47.
In the figure, ABCD is a trapezium of area 24.5 cm2. In it, AD || BC, ∠DAB = 90°, AD = 10 cm and BC = 4 cm. If ABE is a quadrant of a circle, find the area of the shaded region. (Take π – (22/7). [ cbse2014]
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 105
Solution:
In the figure, ABCD is a trapezium
Area = 24.5 cm2, AD || BC
∠DAB = 90°, AD = 10 cm BC = 4 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 106
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 107

Question 48.
In the figure, ABCD is a trapezium with AB || DC, AB = 18 cm, DC = 32 cm and the distance between AB and DC is 14 cm. Circles of equal radii 7 cm with centres A, B, C and D have been drawn. Then, find the area of the shaded region of the figure. (Use π  = 22/7). [CBSE 2014]
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 108
Solution:
In trapezium ABCD
AB || DC
AB = 18 cm, DC = 32 cm Height = 14 cm
Radius of each at the corner of trapezium = 7 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 109
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 110

Question 49.
From a thin metallic piece, in the shape of a trapezium ABCD, in which AB || CD and ∠BCD = 90°, a quarter circle BEFC is removed (see figure). Given AB = BC = 3.5 cm and DE = 2 cm, calculate the area of the remaining piece of the metal sheet.
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 111
Solution:
ABCD is a trapezium in shape in which
AB || CD and ∠BCD = 90°
AB = BC = 3.5 cm, DE = 2 cm
∴ DC = DE + EC = DE + BC = 2 + 3.5 = 5.5 cm
Now area of trapezium ABCD = \(\frac { 1 }{ 2 }\) (AB + CD) x BC (∵ BC is height)
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 112
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 113

Question 50.
In the figure, ABC is an equilateral triangle of side 8 cm. A, B and C are the centres of circular arcs of radius 4 cm. Find the area of the shaded region correct upto 2 decimal places. (Take π = 3.142
and \(\sqrt { 3 } \)  = 1.732).
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 114
Solution:
In the figure, ABC is an equilateral triangle with 8 cm as side with centres A, B and C,
circular arcs drawn of radius 4 cm
Each side of ΔABC = 8 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 115
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 116

Question 51.
Sides of a triangular field are 15 m, 16 m and 17 m. With the three corners of the field a cow, a buffalo and a horse are tied separately with ropes of length 7 m each to graze in the field. Find the area of the field which cannot be grazed by three animals. (NCERT Exemplar)
Solution:
Given that, a triangular field with the three comers of the field a cow, a buffalo and a horse are tied separately with ropes. So, each animal grazed the field in each corner of triangular field as a sectorial form.
Given, radius of each sector (r) = 7m
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 117
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 118
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 119
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 120
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 121

Question 52.
In the given figure, the side of a square is 28 cm, and radius of each circle is half of the length of the side of the square where O and O’ are centres of the circles. Find the area of shaded region. [CBSE 2017]
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 122
Solution:
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 123

Question 53.
In a hospital used water is collected in a cylindrical tank of diameter 2 m and height 5 m. After recycling, this water is used to irrigate a park to hospital whose length is 25 m and breadth is 20 m. If tank is filled completely then what will be the height of standing water used for irrigating the park? [CBSE 2017]
Solution:
Diameter of cylinder (d) = 2 m
Radius of cylinder (r) = 1 m
Height of cylinder (H) = 5 m
Volume of cylindrical tank, Vc = = πr²H = π X (1) 2 X 5= 5πm
Length of the park (L) = 25 m
Now water from the tank is used to irrigated the park. So, volume of cylindrical tank = Volume of water in the park.
⇒ 5π = 25 x 20 x h
⇒ 5π/25 x 20 = h
⇒ h = π/100 m
⇒ h = 0.0314 m
Through recycling of water, better use of the natural resource occurs without wastage. It helps in  reducing and preventing pollution.
It thus helps in conserving water. This keeps the greenery alive in urban areas like in parks gardens etc.

Hope given RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.4 are helpful to complete your math homework.

If you have any doubts, please comment below. Learn Insta try to provide online math tutoring for you.

RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3

RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3

These Solutions are part of RD Sharma Class 10 Solutions. Here we have given RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3

Other Exercises

 

Question 1.
Find the coordinates of the point which divides the line segment joining (-1, 3) and (4, -7) internally in the ratio 3 : 4.
Solution:
The line segment joining the points A (-1,3) and B (4, -7) is divided into the ratio 3 : 4
Let P (x, y) divides AB in the ratio 3 : 4
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 1
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 2

Question 2.
Find the points of trisection of the line segment joining the points :
(i) (5, -6) and (-7, 5)
(ii) (3, -2) and (-3, -4)
(iii) (2, -2) and (-7, 4) [NCERT]
Solution:
(i) The line segment whose end points are A (5, -6) and B (-7,5) which is trisected at C and D
C divides it in the ratio 1 : 2
i.e., AC : CB = 1 : 2
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 3
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 4
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 5
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 6

Question 3.
Find the coordinates of the point where the diagonals of the parallelogram formed by joining the points (-2, -1), (1, 0) (4,3) and (1, 2) meet.
Solution:
Let the vertices of the parallelogram ABCD be A (-2, -1), B (1, 0), C (4, 3) and D (1, 2) in which AC and BD are its diagonals which bisect each other at O
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 7

Question 4.
Prove that the points (3, -2), (4, 0), (6, -3) and (5, -5) are the vertices of a parallelogram.
Solution:
Let the vertices of the quadrilateral ABCD be A (3, -2), B (4, 0), C (6, -3) and D (5, -5)
Now co-ordinates of the mid-point of AC
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 8
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 9

Question 5.
If P (9a – 2, -b) divides the line segment joining A (3a + 1, -3) and B (8a, 5) in the ratio 3 : 1, find the values of a and b. [NCERT Exemplar]
Solution:
Let P (9a – 2, -b) divides AB internally in the ratio 3 : 1.
By section formula,
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 10
=> 9a – 9 = 0
a = 1

Question 6.
If (a, b) is the mid-point of the line segment joining the points A (10, -6), B (k, 4) and a – 2b = 18, find the value of k and the distance AB. [NCERT Exemplar]
Solution:
Since, (a, b) is the mid-point of line segment AB.
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 11
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 12
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 13

Question 7.
Find the ratio in which the points (2, y) divides the line segment joining the points A (-2, 2) and B (3, 7). Also, find the value of y. (C.B.S.E. 2009)
Solution:
Let the point P (2, y) divides the line segment joining the points A (-2, 2) and B (3, 7) in the ratio m1 : m2
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 14

Question 8.
If A (-1, 3), B (1, -1) and C (5, 1) are the vertices of a triangle ABC, find the length of the median through A.
Solution:
In ∆ABC, the vertices are A (-1, 3), B (1, -1) and C (5, 1)
D is the mid-point of BC
Co-ordinates of D will be (\(\frac { 1 + 5 }{ 2 }\) , \(\frac { -1 + 1 }{ 2 }\))
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 15

Question 9.
If the points P, Q (x, 7), R, S (6, y) in this order divide the line segment joining A (2, p) and B (7,10) in 5 equal parts, find x, y and p. [CBSE 2015]
Solution:
Points P, Q (x, 7), R, S (6, y) in order divides a line segment joining A (2, p) and B (7, 10) in 5 equal parts
i.e., AP = PQ = QR = RS = SB
Q is the mid point of A and S
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 16

Question 10.
If a vertex of a triangle be (1, 1) and the middle points of the sides through it be (-2, 3) and (5, 2), find the other vertices.
Solution:
Let co-ordinates of one vertex A are (1, 1) and mid-points of AB and AC are D (-2, 3) and E (5, 2)
Let the co-ordinates of B be (x1, y1) and C be (x2, y2)
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 17
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 18

Question 11.
(i) In what ratio is the line segment joining the points (-2, -3) and (3, 7) divided by the y-axis ? Also find the co-ordinates of the point of division. [CBSE 2006C]
(ii) In what ratio is the line segment joining (-3, -1) and (-8, -9) divided at the point (-5, \(\frac { -21 }{ 5 }\)) ?
Solution:
(i) The point lies on y-axis
Its abscissa is O
Let the point (0, y) intersects the line joining the points (-2, -3) and (3, 7) in the ratio m : n
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 19
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 20
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 21

Question 12.
If the mid-point of the line joining (3, 4) and (k, 7) is (x, y) and 2x + 2y + 1 = 0, find the value of k.
Solution:
Mid-point of the line joining the points (3, 4) and (k, 7) is (x, y)
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 22

Question 13.
Find the ratio in which the points P (\(\frac { 3 }{ 4 }\) , \(\frac { 5 }{ 12 }\)) divides the line segments joining the points A (\(\frac { 1 }{ 2 }\) , \(\frac { 3 }{ 2 }\)) and B (2, -5). [CBSE 2015]
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 23
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 24

Question 14.
Find the ratio in which the line segment joining (-2, -3) and (5, 6) is divided by (i) x-axis (ii) y-axis. Also, find the co-ordinates of the point of division in each case.
Solution:
(i) Ordinate of a point on x-axis is zero
Let the co-ordinate of the point on x-axis be (0, x)
But (x, 0) is a point which divides the line segment joining the points (-2, -3) and (5, 6) in the ratio m : n
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 25
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 26
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 27

Question 15.
Prove that the points (4, 5), (7, 6), (6, 3), (3, 2) are the vertices of a parallelogram. Is it a rectangle ?
Solution:
The vertices of a parallelogram ABCD are A (4, 5), B (7, 6), C (6, 3), and D (3, 2)
The diagonals AC and BD bisect each other at O
O is the mid-point of AC as well as of BD
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 28
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 29
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 30

Question 16.
Prove that (4, 3), (6, 4), (5, 6) and (3, 5) are the angular points of a square.
Solution:
Let A (4, 3), B (6, 4), C (5, 6) and D (3, 5) are the vertices of a square ABCD.
AC and BD are its diagonals which bisects each other at O.
O is the mid-point of AC
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 31
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 32
The diagonals of the quadrilateral ABCD are equal and bisect eachother at O and sides are equal
ABCD is a square

Question 17.
Prove that the points (-4, -1), (-2, -4), (4, 0) and (2, 3) are the vertices of a rectangle.
Solution:
Let the vertices of a quadrilateral ABCD are A (-4, -1), B (-2, -4), C (4, 0) and D (2, 3)
Join AC and BD which intersect eachother at O
If O is the mid-point of AC then its co
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 33
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 34

Question 18.
Find the lengths of the medians of a triangle whose vertices are A (-1, 3), B (1, -1) and C (5, 1).
Solution:
The co-ordinates of the vertices of ∆ABC are A (-1, 3), B (1, -1) and C (5, 1)
D, E and F are the mid-points of sides BC, CA and AB respectively
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 35
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 36

Question 19.
Find the ratio in which the line segment joining the pionts A (3, -3) and B (-2, 7) is divided by x-axis. Also, find the coordinates of the point of division. [CBSE 2014]
Solution:
Let a point P (x, 0)
x-axis divides the line segment joining the points A (3, -3) and B (-2, 7) in the ratio m1 : m2
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 37
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 38

Question 20.
Find the ratio in which the point P (x, 2) divides the line segment joining the points A (12, 5) and B (4, -3). Also, find the value of x. [CBSE 2014]
Solution:
Let P (x, 2) divides the line segment joining the points A (12, 5) and B (4, -3) in the ratio m1 : m2
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 39

Question 21.
Find the ratio in which the point P (-1, y) lying on the line segment joining A (-3, 10) and B (6, -8) divides it. Also find the value of y.
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 40

Question 22.
Find the coordinates of a point A, where AB is a diameter of the circle whose centre is (2, -3) and B is (1, 4).
Solution:
AB is the diameter of the circle and O is the centre of the circle
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 41
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 42

Question 23.
If the points (-2, -1), (1, 0), (x, 3) and (1, y) form a parallelogram, find the values of x and y.
Solution:
In ||gm ABCD, co-ordinates of A (-2, -1), B (1, 0),C(x, 3) and D(1, y)
AC and BD are its diagonals which bisect eachother at O
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 43
x = 4, y = 2

Question 24.
The points A (2, 0), B (9, 1), C (11, 6) and D (4, 4) are the vertices of a quadrilateral ABCD. Determine whether ABCD is a rhombus or not.
Solution:
The co-ordinates of vertices of a quadrilateral ABCD are A (2,0), B (9,1), C (11,6) and D (4, 4)
AC and BD are its diagonals which intersect eachother at O
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 44
The co-ordinates of O in both cases are not same.
It is not a parallelogram and also not a rhombus.

Question 25.
In what ratio does the point (-4, 6) divide the line segment joining the points A (-6, 10) and B (3, -8) ?
Solution:
Let the point P (-4, 6) divides the line segment joining the points A (-6, 10) and B (3, -8) in the ratio m1 : m2
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 45

Question 26.
Find the ratio in which the y-axis divides the line segment joining the points (5, -6) and (-1, -4). Also, find the coordinates of the point of division.
Solution:
The points lies on y-axis
Let its coordinates be (0, y)
and let it divides the line segment joining the points (5, -6) and (-1, -4) in the ratio m1 : m2
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 46

Question 27.
Show that A (-3, 2), B (-5, -5), C (2, -3) and D (4, 4) are the vertices of a rhombus.
Solution:
Vertices of a quadrilateral ABCD are A (-3, 2), B (-5, -5), C (2, -3) and D (4, 4)
Join the diagonals AC and BD which intersect each other at O
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 47
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 48
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 49

Question 28.
Find the lengths of the medians of a ∆ABC having vertices A (0, -1), B (2, 1) and C (0, 3).
Solution:
A (0, -1), B (2, 1) and C (0, 3) are the vertices of ∆ABC
Let D, E and F are the mid points of BC, CA and AB respectively
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 50
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 51

Question 29.
Find the lengths of the medians of a ∆ABC, having the vertices at A (5, 1), B (1, 5) and C (3,-1).
Solution:
A (5, 1), B (1, 5) and C (3, -1) are the vertices of ∆ABC
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 52
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 53

Question 30.
Find the co-ordinates of the points which divide the line segment joining the points (-4, 0) and (0, 6) in four equal parts.
Solution:
AB is a line segment whose ends points are A (-4, 0) and B (0, 6)
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 54
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 55

Question 31.
Show that the mid-point of the line segment joining the points (5, 7) and (3, 9) is also the mid-point of the line segment joining the points (8, 6) and (0, 10).
Solution:
Let M be the mid point of AB. Co-ordinates of the mid point of this line segment joining two points A (5, 7) and B (3, 9)
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 56

Question 32.
Find the distance of the point (1, 2) from the mid-point of the line segment joining the points (6, 8) and (2, 4).
Solution:
Let M be the mid-point of the line segment joining the points (6, 8) and (2, 4)
Now co-ordinates of M will be
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 57
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 58

Question 33.
If A and B are (1, 4) and (5, 2) respectively, find the co-ordinates of P When \(\frac { AP }{ BP }\) = \(\frac { 3 }{ 4 }\)
Solution:
Point P divides the line segment joining the points (1, 4) and (5, 2) in the ratio of AP : PB = 3 : 4
Co-ordinates of P will be
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 59

Question 34.
Show that the points A (1, 0), B (5, 3), C (2, 7) and D (-2, 4) are the vertices of a parallelogram.
Solution:
If ABCD is a parallelogram, then its diagonal
AC and BD bisect eachother at O
Let O is the mid-point of AC, then co
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 60
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 61

Question 35.
Determine the ratio in which the point P (m, 6) divides the join of A (-4, 3) and B (2, 8). Also find the value of m. [CBSE 2004]
Solution:
Let the ratio be r : s in which P (m, 6) divides the line segment joining the points A (-4, 3) and B (2, 8)
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 62
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 63

Question 36.
Determine the ratio in which the point (-6, a) divides the join of A (-3, -1) and B (-8, 9). Also find the value of a. [CBSE 2004]
Solution:
Let the point P (-6, a) divides the join of A (-3, -1) and B (-8, 9) in the ratio m : n
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 64

Question 37.
ABCD is a rectangle formed by joining the points A (-1, -1), B (-1, 4), C (5, 4) and D (5, -1). P, Q, R and S are the mid-points of sides AB, BC, CD and DA respectively. Is the quadrilateral PQRS a square ? a rectangle ? or a rhombus ? Justify your answer.
Solution:
ABCD is a rectangle whose vertices are A (-1,-1), B (-1,4), C (5, 4) and D (5, -1) P, Q, R, and S are the mid-points of the sides AB, BC, CD and DA respectively and are joined PR and QS are also joined.
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 65
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 66
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 67
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 68

Question 38.
Points P, Q, R and S divide the line segment joining the pionts A (1, 2) and B (6, 7) in 5 equal parts. Find the coordinates of the points P, Q and R. [CBSE 2014]
Solution:
Points P, Q, R and S divides AB in 5 equal parts and let coordinates of P, Q, R and S be
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 69
Coordinates of R are (4, 5)

Question 39.
If A and B are two points having co-ordinates (-2, -2) and (2, -4) respectively, find the co-ordinates of P such that AP = \(\frac { 3 }{ 7 }\) AB
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 70
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 71

Question 40.
Find the co-ordinates of the points which divide the line segment joining A (-2, 2) and B (2, 8) into four equal parts.
Solution:
Let P, Q and R divides the line segment AB in four equal parts
Co-ordinates of A are (-2, 2) and of B are (2, 8)
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 72
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 73

Question 41.
Three consecutive vertices of a parallelogram are (-2, -1), (1, 0) and (4, 3). Find the fourth vertex.
Solution:
Let the co-ordinates of three vertices are A (-2, -1), B (1, 0) and C (4, 3)
and let the diagonals AC and BD bisect each other at O
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 74
and \(\frac { y }{ 2 }\) = 1 => y = 2
Co-ordinates of D will be (1, 2)

Question 42.
The points (3, -4) and (-6, 2) are the extremities of a diagonal of a parallelogram. If the third vertex is (-1, -3). Find the co-ordinates of the fourth vertex.
Solution:
Let the extremities of a diagonal AC of a parallelogram ABCD are A (3, -4) and C (-6, 2)
Let AC and BD bisect eachother at O
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 75
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 76

Question 43.
If the co-ordinates of the mid-points of the sides of a triangle are (1, 1), (2, -3) and (3, 4), find the vertices of the triangle.
Solution:
Let A (x1, y1), B (x2, y2) and C (x3, y3) be the vertices of the ∆ABC
D, E and F are the mid-points of BC, CA and AB respectively such that their co-ordinates are D (1, 1), E (2, -3) and F (3, 4)
D is mid-point of BC
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 77
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 78
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 79

Question 44.
Determine the ratio in which the straight line x – y – 2 = 0 divides the line segment joining (3, -1) and (8, 9).
Solution:
Let the straight line x – y – 2 = 0 divides the line segment joining the points (3, -1), (8, 9) in the ratio m : n
Co-ordinates of the point will be
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 80

Question 45.
Three vertices of a parallelogram are (a + b, a – b), (2 a + b, 2a – b), (a – b, a + b). Find the fourth vertex.
Solution:
In parallelogram ABCD co-ordinates are of A (a + b, a – b), B (2a + b, 2a – b), C (a – b, a + b)
Let co-ordinates of D be (x, y)
Join diagonal AC and BD
Which bisect eachother at O
O is the mid-point of AC as well as BD
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 81
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 82

Question 46.
If two vertices of a parallelogram are (3, 2), (-1, 0) and the diagonals cut at (2, -5), find the other vertices of the parallelogram.
Solution:
Two vertices of a parallelogram ABCD are A (3,2), and B (-1, 0) and its diagonals bisect each other at O (2, -5)
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 83
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 84

Question 47.
If the co-ordinates of the mid-points of the sides of a triangle ar6 (3, 4), (4, 6) and (5, 7), find its vertices. [CBSE 2008]
Solution:
The co-ordinates of the mid-points of the sides BC, CA and AB are D (3, 4), E (4, 6) and F (5, 7) of the ∆ABC
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 85
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 86
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 87

Question 48.
The line segment joining the points P (3, 3) and Q (6, -6) is trisected at the points A and B such that A is nearer to P. If A also lies on the line given by 2x + y + k = 0, find the value of k. [CBSE 2009]
Solution:
Two points A and B trisect the line segment joining the points P (3, 3) and Q (6, -6) and A is nearer to P
and A lies also on the line 2x + y + k = 0
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 88
=> k = -8
Hence k = -8

Question 49.
If three consecutive vertices of a parallelogram are (1, -2), (3, 6) and (5, 10), find its fourth vertex.
Solution:
A (1, -2), B (3, 6) and C (5, 10) are the three consecutive vertices of the parallelogram ABCD
Let (x, y) be its fourth vertex
AC and BD are its diagonals which bisect each other at O
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 89

Question 50.
If the points A (a, -11), B (5, b), C (2, 15) and D (1, 1) are the vertices of a parallelogram ABCD, find the values of a and b.
Solution:
A (a, -11), B (5, b), C (2, 15) and D (1, 1) are the vertices of a parallelogram ABCD
Diagonals AC and BD bisect eachother at O
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 90
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 91

Question 51.
If the co-ordinates of the mid-points of the sides of a triangle be (3, -2), (-3, 1) and (4, -3), then find the co-ordinates of its vertices.
Solution:
In a ∆ABC,
D, E and F are the mid-points of the sides BC, CA and AB respectively and co-ordinates of D, E and F are (3, -2), (-3, 1) and (4, -3) respectively
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 92
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 93
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 94

Question 52.
The line segment joining the points (3, -4) and (1, 2) is trisected at the points P and Q. If the co-ordinates of P and Q are (p, -2) and (\(\frac { 5 }{ 3 }\) , q) respectively, find the values of p and q. [CBSE 2005]
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 95

Question 53.
The line joining the points'(2, 1), (5, -8) is trisected at the points P and Q. If point P lies on the line 2x – y + k = 0, find the value of k. [CBSE 2005]
Solution:
Points A (2, 1), and B (5, -8) are the ends points of the line segment AB
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 96

Question 54.
A (4, 2), B (6, 5) and C (1, 4) are the vertices of ∆ABC,
(i) The median from A meets BC in D. Find the coordinates of the point D.
(ii) Find the coordinates of point P on AD such that AP : PD = 2 : 1.
(iii) Find the coordinates of the points Q and R on medians BE and CF respectively such that BQ : QE = 2 : 1 and CR : RF = 2 : 1.
(iv) What do you observe? [NCERT,CBSE, 2009, 10]
Solution:
In ∆ABC, co-ordinates of A (4, 2) of (6, 5) and of (1, 4) and AD is BE and CF are the medians such that D, E and F are the mid points of the sides BC, CA and AB respectively
P is a point on AD such that AP : PD = 2 : 1
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 97
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 98
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 99
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 100
(iv) We see that co-ordinates of P, Q and R are same i.e., P, Q and R coincides eachother. Medians of the sides of a triangle pass through the same point which is called the centroid of the triangle.

Question 55.
If the points A (6, 1), B (8, 2), C (9, 4) and D (k, p) are the vertices of a parallelogram taken in order, then find the values of k and p.
Solution:
The diagonals of a parallelogram bisect each other
O is the mid-point of AC and also of BD
O is the mid-point of AC
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 101

Question 56.
A point P divides the line segment joining the points A (3, -5) and B (-4, 8) such that \(\frac { AP }{ PB }\) = \(\frac { k }{ 1 }\). If P lies on the line x + y = 0, then find the value of k. [CBSE 2012]
Solution:
Point P divides the line segment by joining the points A (3, -5) and B (-4, 8)
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 102
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 103

Question 57.
The mid-point P of the line segment joining the points A (-10, 4) and B (-2, 0) lies on the line segment joining the pionts C (-9, -4) and D (-4, y). Find the ratio in which P divides CD. Also, find the value of y. [CBSE 2014]
Solution:
P is the mid-point of line segment joining the points A (-10, 4) and B (-2, 0)
Coordinates of P will be
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 104
=> y = \(\frac { 18 }{ 3 }\) = 6
y = 6

Question 58.
If the point C (-1, 2) divides internally the line segment joining the points A (2, 5) and B (x, y) in the ratio 3 : 4, find the value of x² + y². [CBSE 2016]
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 105

Question 59.
ABCD is a parallelogram with vertices A (x1, y1), B (x2, y2) and C (x3, y3). Find the coordinates of the fourth vertex D in terms of x1, x2, x3, y1, y2 and y3. [NCERT Exemplar]
Solution:
Let the coordinates of D be (x, y). We know that diagonals of a parallelogram bisect each other.
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 106
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 107

Question 60.
The points A (x1, y1), B (x2, y2) and C (x3, y3) are the vertices of ∆ABC.
(i) The median from A meets BC at D. Find the coordinates of the point D.
(ii) Find the coordinates of the point P on AD such that AP : PD = 2 : 1.
(iii) Find the points of coordinates Q and R on medians BE and CF respectively such that BQ : QE = 2 : 1 and CR : RF = 2 : 1.
(iv) What are the coordinates of the centroid of the triangle ABC? [NCERT Exemplar]
Solution:
Given that, the points A (x1, y1), B (x2, y2) and C (x3, y3) are the vertices of ∆ABC.
(i) We know that, the median bisect the line segment into two equal parts i.e., here D is the mid-point of BC.
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 108
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 109
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 110
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 111

Hope given RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.3 are helpful to complete your math homework.

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RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1

RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1

These Solutions are part of RD Sharma Class 10 Solutions. Here we have given RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1

Other Exercises

Question 1.
In each of the following, one of the six trigonometric ratios is given. Find the values of the other trigonometric ratios.
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 1
Solution:
∴ Perpendicular BC – 2 units and
Hypotenuse AC = 3 units
By Phythagoras Theorem, in AABC,
(Hypotenuse)2 = (Base)2 + (Perpendicular)2
AC2 = AB2 + BC2
⇒ (3)2 = (AB)2 + (2)2
⇒ 9 = AB2 + 4 ⇒ AB2 = 9-4 = 5
AB = √5 units
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 2
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 3
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 4
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 5
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 6
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 7
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 8
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 9
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 10
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 11
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 12
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 13
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 14
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 15
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 16
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 17
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 18
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 19
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 20

Question 2.
In a ΔABC, right angled at B, AB = 24 cm, BC = 7 cm. Determine
(i) sin A, cos A
(ii) sin C, cos C.

Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 21

Question 3.
In the figure, find tan P and cot R. Is tan P = cot R ?
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 22
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 23

Question 4.
If sin A = \(\frac { 9 }{ 41 }\), compute cos A and tan A.
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 24

Question 5.
Given 15 cot A = 8, find sin A and sec A.
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 25

Question 6.
In ΔPQR, right angled at Q, PQ = 4 cm and RQ = 3 cm. Find the values of sin P, sin R, sec P and sec R.
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 26
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 27

Question 7.
If cot 0 = \(\frac { 7 }{ 8 }\), evaluate :
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 28
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 29
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 30
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 31

Question 8.
If 3 cot A = 4, check whether \(\frac { 1-{ tan }^{ 2 }A }{ 1+{ tan }^{ 2 }A }\) = cos2 A – sin2 A or not.
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 32
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 33

Question 9.
If tan θ = a/b , Find the Value of \(\frac { cos\theta +sin\theta }{ cos\theta -sin\theta }\).
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 34
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 35

Question 10.
If 3 tan θ = 4, find the value of 4cos θ – sin θ \(\frac { 4cos\theta -sin\theta }{ 2cos\theta +sin\theta }\).
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 36
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 37

Question 11.
If 3 cot 0 = 2, find the value of \(\frac { 4sins\theta -3cos\theta }{ 2sin\theta +6cos\theta }\).
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 38

Question 12.
If tan θ = \(\frac { a }{ b }\), prove that
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 39
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 40

Question 13.
If sec θ = \(\frac { 13 }{ 5 }\), show that \(\frac { 2sins\theta -3cos\theta }{ 4sin\theta -9cos\theta }\) =3.
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 41

Question 14.
If cos θ \(\frac { 12 }{ 13 }\), show that sin θ (1 – tan θ) \(\frac { 35 }{ 156 }\).
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 42
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 43

Question 15.
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 44
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 45
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 46

Question 16.
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 47
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 48
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 49

Question 17.
If sec θ = \(\frac { 5 }{ 4 }\), find the value of \(\frac { sins\theta -2cos\theta }{ tan\theta -cot\theta }\).
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 50
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 51

Question 18.
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 52
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 53
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 54

Question 19.
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 55
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 56
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 57

Question 20.
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 58
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 59
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 60

Question 21.
If tan θ = \(\frac { 24 }{ 7 }\), find that sin θ + cos θ.
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 61
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 62

Question 22.
If sin θ = \(\frac { a }{ b }\), find sec θ + tan θ in terms of a and b.
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 63

Question 23.
If 8 tan A = 15, find sin A – cos A.
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 64

Question 24.
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 65
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 66
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 67

Question 25.
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 68
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 69
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 70

Question 26.
If ∠A and ∠B are acute angles such that cos A = cos B, then show that ∠A = ∠B.
Solution:
∠A and ∠B are acute angles and cos A = cos B
Draw a right angle AABC, in which ∠C – 90°
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 71

Question 27.
In a ∆ABC, right angled at A, if tan C =√3 , find the value of sin B cos C + cos B sin C. (C.B.S.E. 2008)
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 72
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 73

Question 28.
28. State whether the following are true or false. Justify your answer.
(i) The value of tan A is always less than 1.
(ii) sec A = \(\frac { 12 }{ 5 }\) for some value of angle A.
(iii) cos A is the abbreviation used for the cosecant of angle A.
(iv) cot A is the product of cot and A.
(v) sin θ = \(\frac { 4 }{ 3 }\) for some angle θ.
Solution:
(i) False, value of tan A 0 to infinity.
(ii) True.
(iii) False, cos A is the abbreviation of cosine A.
(iv) False, it is the cotengent of angle A.
(v) Flase, value of sin θ varies on 0 to 1.

Question 29.
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 74
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 75
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 76
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 77

Question 30.
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 78
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 79
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 80

Question 31.
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 81
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 82
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 83

Question 32.
If sin θ =\(\frac { 3 }{ 4 }\), prove that
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 84
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 85
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 86

Question 33.
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 87
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 88
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 89

Question 34.
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 90
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 91
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 92
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 93

Question 35.
If 3 cos θ-4 sin θ = 2 cos θ + sin θ, find tan θ.
Solution:
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 94

Question 36.
If ∠A and ∠P are acute angles such that tan A = tan P, then show that ∠A = ∠P.
Solution:
∠A and ∠P are acute angles and tan A = tan P Draw a right angled AAPB in which ∠B = 90°
RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 95

 

Hope given RD Sharma Class 10 Solutions Chapter 10 Trigonometric Ratios Ex 10.1 are helpful to complete your math homework.

If you have any doubts, please comment below. Learn Insta try to provide online math tutoring for you.

RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2

RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2

These Solutions are part of RD Sharma Class 10 Solutions. Here we have given RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2

Other Exercises

Question 1.
Find the distance between the following pair of points :
(i) (-6, 7) and (-1, -5)
(ii) (a + b, b + c) and (a – b, c – b)
(iii) (a sin α, -b cos α) and (-a cos α, -b sin α)
(iv) (a, 0) and (0, b)
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 1
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 2
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 3

Question 2.
Find the value of a when the distance between the points (3, a) and (4, 1) is √10
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 4
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 5

Question 3.
If the points (2, 1) and (1, -2) are equidistant from the point (x, y), show that x + 3y = 0.
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 6

Question 4.
Find the values of x, y if the distances of the point (x, y) from (-3, 0) as well as from (3, 0) are 4.
Solution:
Distance between (x, y) and (-3, 0) is
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 7
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 8

Question 5.
The length of a line segment is of 10 units and the coordinates of one end-point are (2, -3). If the abscissa of the other end is 10, find the ordinate of the other end.
Solution:
Let the ordinate of other end by y, then The distance between (2, -3) and (10, y) is
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 9
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 10

Question 6.
Show that the points (-4, -1), (-2, -4), (4, 0) and (2, 3) are the vertices points of a rectangle. (C.B.S.E. 2006C)
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 11
AB = CD and AD = BC
and diagonal AC = BD
ABCD is a rectangle

Question 7.
Show that the points A (1, -2), B (3, 6), C (5, 10) and D (3, 2) are the vertices of a parallelogram.
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 12

Question 8.
Prove that the points A (1, 7), B (4, 2), C (-1, -1) and D (-4, 4) are the vertices of a square. [NCERT]
Solution:
Vertices A (1, 7), B (4, 2), C (-1,-1), D (-4, 4)
If these are the vertices of a square, then its diagonals and sides are equal
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 13
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 14

Question 9.
Prove that the points (3, 0), (6, 4) and (-1, 3) are the vertices of a right-angled isosceles triangle. (C.B.S.E. 2006C)
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 15
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 16

Question 10.
Prove that (2, -2), (-2, 1) and (5, 2) are the vertices of a right angled triangle. Find the area of the triangle and the length of the hypotenuse.
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 17
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 18

Question 11.
Prove that the points (2a, 4a), (2a, 6a) and (2a + √3 a , 5a) are the vertices of an equilateral triangle.
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 19

Question 12.
Prove that the points (2, 3), (-4, -6) and (1, \(\frac { 3 }{ 2 }\) )do not form a triangle.
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 20
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 21

Question 13.
The points A (2, 9), B (a, 5) and C (5, 5) are the vertices of a triangle ABC right angled at B. Find the values of a and hence the area of ∆ABC. [NCERT Exemplar]
Solution:
Given that, the points A (2, 9), B (a, 5) and C (5, 5) are the vertices of a ∆ABC right angled at B.
By Pythagoras theorem, AC² = AB² + BC² ………(i)
Now, by distance formula,
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 22
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 23

Question 14.
Show that the quadrilateral whose vertices are (2, -1), (3, 4), (-2, 3) and (-3, -2) is a rhombus.
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 24
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 25

Question 15.
Two vertices of an isosceles triangle are (2, 0) and (2, 5). Find the third vertex if the length of the equal sides is 3.
Solution:
Two vertices of an isosceles ∆ABC are A (2, 0) and B (2, 5). Let co-ordinates of third vertex C be (x, y)
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 26
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 27
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 28
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 29

Question 16.
Which point on x-axis is equidistant from (5, 9) and (-4, 6) ?
Solution:
Let co-ordinates of two points are A (5, 9), B (-4, 6)
The required point is on x-axis
Its ordinates or y-co-ordinates will be 0
Let the co-ordinates of the point C be (x, 0)
AC = CB
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 30
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 31

Question 17.
Prove that the point (-2, 5), (0, 1) and (2, -3) are collinear.
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 32
Now AB + BC = 2√5 +2√5
and CA = 4√5
AB + BC = CA
A, B and C are collinear

Question 18.
The co-ordinates of the point P are (-3,2). Find the co-ordinates of the point Q which lies on the line joining P and origin such that OP = OQ.
Solution:
Co-ordinates of P are (-3, 2) and origin O are (0, 0)
Let co-ordinates of Q be (x, y)
O is the mid point of PQ
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 33
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 34
= 9 + 4 = (±3)² + (±2)²
The point will be in fourth quadrant
Its y-coordinates will be negative
and x-coordinates will be positive
Now comparing the equation
x² = (±3)² => x = ±3
y² = (±2)² => y = ±2
x = 3, y = -2
Co-ordinates of the point Q are (3, -2)

Question 19.
Which point on y-axis is equidistant from (2, 3) and (-4, 1) ?
Solution:
The required point lies on y-axis
Its abscissa will be zero
Let the point be C (0, y) and A (2, 3), B (-4, 1)
Now,
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 35

Question 20.
The three vertices of a parallelogram are (3, 4), (3, 8) and (9, 8). Find the fourth vertex.
Solution:
Let ABCD be a parallelogram and vertices will be A (3, 4), B (3, 8), C (9, 8)
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 36
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 37
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 38
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 39

Question 21.
Find a point which is equidistant from the point A (-5, 4) and B (-1, 6). How many such points are there? [NCERT Exemplar]
Solution:
Let P (h, k) be the point which is equidistant from the points A (-5, 4) and B (-1, 6).
PA = PB
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 40
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 41
So, the mid-point of AB satisfy the Eq. (i).
Hence, infinite number of points, in fact all points which are solution of the equation 2h + k + 1 = 0, are equidistant from the point A and B.
Replacing h, k, by x, y in above equation, we have 2x + y + 1 = 0

Question 22.
The centre of a circle is (2a, a – 7). Find the values of a if the circle passes through the point (11, -9) and has diameter 10√2 units. [NCERT Exemplar]
Solution:
By given condition,
Distance between the centre C (2a, a-1) and the point P (11, -9), which lie on the circle = Radius of circle
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 42
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 43

Question 23.
Ayush starts walking from his house to office. Instead of going to the office directly, he goes to a bank first, from there to his daughter’s school and then reaches the office. What is the extra distance travelled by Ayush in reaching the office? (Assume that all distance covered are in straight lines). If the house is situated at (2, 4), bank at (5, 8), school at (13, 14) and office at (13, 26) and coordinates are in kilometers. [NCERT Exemplar]
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 44
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 45
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 46

Question 24.
Find the value of k, if the point P (0, 2) is equidistant from (3, k) and (k, 5).
Solution:
Let P (0, 2) is equidistant from A (3, k) and B (k, 5)
PA = PB
=> PA² = PB²
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 47

Question 25.
If (-4, 3) and (4, 3) are two vertices of an equilateral triangle, find the coordinates of the third vertex, given that the origin lies in the
(i) interior,
(ii) exterior of the triangle. [NCERT Exemplar]
Solution:
Let the third vertex of an equilateral triangle be (x, y).
Let A (-4, 3), B (4,3) and C (x, y).
We know that, in equilateral triangle the angle between two adjacent side is 60 and all three sides are equal.
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 48
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 49
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 50
But given that, the origin lies in the interior of the ∆ABC and the x-coordinate of third vertex is zero.
Then, y-coordinate of third vertex should be negative.
Hence, the require coordinate of third vertex,
C = (0, 3 – 4√3). [C ≠ (0, 3 + 4√3)]

Question 26.
Show that the points (-3, 2), (-5, -5), (2, -3) and (4, 4) are the vertices of a rhombus. Find the area of this rhombus.
Solution:
Let the co-ordinates of the vertices A, B, C and D of a rhombus are A (-3, 2), B (-5, -5), C (2, -3) and D (4, 4)
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 51
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 52

Question 27.
Find the coordinates of the circumcentre of the triangle whose vertices are (3, 0), (-1, -6) and (4, -1). Also, find its circumradius.
Solution:
Let ABC is a triangle whose vertices are A (3, 0), B (-1, -6) and C (4, -1)
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 53
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 54

Question 28.
Find a point on the x-axis which is equidistant from the points (7, 6) and (-3, 4). [CBSE 2005]
Solution:
The required point is on x-axis
Its ordinate will be O
Let the co-ordinates of the required point P (x, 0)
Let the point P is equidistant from the points A (7, 6) and B (-3, 4)
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 55
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 56

Question 29.
(i) Show that the points A (5, 6), B (1, 5), C (2, 1) and D (6, 2) are the vertices of a square. [CBSE 2004]
(ii) Prove that the points A (2, 3), B (-2, 2), C (-1, -2) and D (3, -1) are the vertices of a square ABCD. [CBSE 2013]
(iii) Name the type of triangle PQR formed by the point P(√2 , √2), Q(- √2, – √2) and R (-√6 , √6 ). [NCERT Exemplar]
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 57
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 58
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 59
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 60

Question 30.
Find the point on x-axis which is equidistant from the points (-2, 5) and (2, -3). [CBSE 2004]
Solution:
The point P lies on x-axis
The ordinates of P will be 0 Let the point P be (x, 0)
Let P is equidistant from A (-2, 5) and B (2, -3)
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 61
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 62

Question 31.
Find the value of x such that PQ = QR where the co-ordinates of P, Q and R are (6, -1) (1, 3) and (x, 8) respectively. [CBSE 2005]
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 63

Question 32.
Prove that the points (0, 0), (5, 5) and (-5, 5) are the vertices of a right isosceles triangle. [CBSE 2005]
Solution:
Let the vertices of a triangle be A (0, 0), B (5, 5) and C (-5, 5)
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 64
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 65

Question 33.
If the points P (x, y) is equidistant from the points A (5, 1) and B (1,5), prove that x = y. [CBSE 2005]
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 66

Question 34.
If Q (0, 1) is equidistant from P (5, -3) and R (x, 6) find the values of x. Also find the distances QR and PR. [NCERT]
Solution:
Q (0, 1) is equidistant from P (5, -3) and R (x, 6)
PQ = RQ
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 67
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 68

Question 35.
Find the values ofy for which the distance between the points P (2, -3) and Q (10, y) is 10 units. [NCERT]
Solution:
Distance between P (2, -3) and Q (10, y) = 10
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 69

Question 36.
If the point P (k – 1, 2) is equidistant from the points A (3, k) and B (k, 5), find the values of k. [CBSE 2014]
Solution:
Point P (k – 1, 2) is equidistant from A (3, k) and B (k, 5)
PA= PB
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 70

Question 37.
If the point A (0, 2) is equidistant from the point B (3, p) and C (p, 5), find p. Also, find the length of AB. [CBSE 2014]
Solution:
Point A (0, 2) is equidistant from B (3, p) and C (p, 5)
AB = AC
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 71

Question 38.
Name the quadrilateral formed, if any, by the following points, and give reasons for your answers :
(i) A (-1, -2), B (1, 0), C (-1, 2), D (-3, 0)
(ii) A (-3, 5), B (3, 1), C (0, 3), D (-1, -4)
(iii) A (4, 5), B (7, 6), C (4, 3), D (1, 2)
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 72
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 73
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 74
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 75

Question 39.
Find the equation of the perpendicular bisector of the line segment joining points (7, 1) and (3, 5).
Solution:
Let the given points are A (7, 1) and B (3, 5) and mid point be M
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 76
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 77

Question 40.
Prove that the points (3, 0), (4, 5), (-1, 4) and (-2, -1) taken in order, form a rhombus. Also find its area.
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 78
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 79

Question 41.
In the seating arrangement of desks in a classroom three students Rohini, Sandhya and Bina are seated at A (3, 1), B (6, 4) and C (8, 6). Do you think they are seated in a line ?
Solution:
A (3, 1), B (6, 4) and C (8, 6)
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 80

Question 42.
Find a point ony-axis which is equidistant from the points (5, -2) and (-3, 2).
Solution:
The point lies on y-axis
Its x = 0
Let the required point be (0, y) and let A (5, -2) and B (-3, 2)
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 81

Question 43.
Find a relation between x and y such that the point (x, y) is equidistant from the points (3, 6) and (-3, 4). [NCERT]
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 82

Question 44.
If a point A (0, 2) is equidistant from the points B (3, p) and C (p, 5), then find the value of p. [CBSE 2012]
Solution:
Point A (0, 2) is equidistant from the points B (3, p) and C (p, 5)
AB = AC
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 83
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 84

Question 45.
Prove that the points (7, 10), (-2, 5) and (3, -4) are the vertices of an isosceles right triangle. [CBSE 2013]
Solution:
Let points are A (7, 10), B (-2, 5) and C (3, -4)
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 85

Question 46.
If the point P (x, 3) is equidistant from the points A (7, -1) and B (6, 8), find the value of x and And the distance AP. [CBSE 2014]
Solution:
Point P (x, 3) is equidistant from the points A (7, -1) and B (6, 8)
PA = PB
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 86
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 87

Question 47.
If A (3, y) is equidistant from points P (8, -3) and Q (7, 6), find the value of y and find the distance AQ. [CBSE 2014]
Solution:
Point A (3, y) is equidistant from P (8, -3) and Q (7, 6)
i.e., AP = AQ
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 88

Question 48.
If (0, -3) and (0, 3) are the two vertices of an equilateral triangle, find the coordinates of its third vertex. [CBSE 2014]
Solution:
Let A (0, -3) and B (0, 3) are vertices of an equilateral triangle
Let the coordinates of the third vertex be C (x, y)
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 89
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 90

Question 49.
If the point P (2, 2) is equidistant from the points A (-2, k) and B (-2k, -3), find k. Also, find the length of AP.
Solution:
Point P (2, 2) is equidistant from the points A (-2, k) and B (-2k, -3)
AP = BP
Now,
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 91
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 92

Question 50.
Show that ∆ABC, where A (-2, 0), B (2, 0), C (0, 2) and ∆PQR, where P (-4, 0), Q (4, 0), R (0, 4) are similar.
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 93
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 94
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 95

Question 51.
An equilateral triangle has two vertices at the points (3, 4), and (-2, 3). Find the co-ordinates of the third vertex.
Solution:
Let two vertices of an equilateral triangle are A (3,4), and B (-2,3) and let the third vertex be C (x, y)
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 96
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 97
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 98
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 99

Question 52.
Find the circumcentre of the triangle whose vertices are (-2, -3), (-1, 0), (7, -6).
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 100
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 101
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 102

Question 53.
Find the angle subtended at the origin by the line segment whose end points are (0, 100) and (10, 0).
Solution:
Let co-ordinates of the end points of a line segment are A (0, 100), B (10, 0) and origin is O (0, 0)
Abscissa of A is 0
It lies on y-axis
Similarly, ordinates of B is 0
It lies on x-axis
But axes intersect each other at right angle
AB will subtended 90° at the origin
Angle is 90° or \(\frac { \pi }{ 2 }\)

Question 54.
Find the centre of the circle passing through (5, -8), (2, -9) and (2, 1).
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 103
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 104
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 105

Question 55.
If two opposite vertices of a square are (5, 4) and (1, -6), find the coordinates of its remaining two vertices.
Solution:
Two opposite points of a square are (5, 4) and (1, -6)
Let ABCD be a square and A (5, 4) and C (1, -6) are the opposite points
Let the co-ordinates of B be (x, y). Join AC
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 106
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 107
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 108

Question 56.
Find the centre of the circle passing through (6, -6), (3, -7) and (3, 3).
Solution:
Let O is the centre of the circle is (x, 7) Join OA, OB and OC
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 109
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 110

Question 57.
Two opposite vertices of a square are (-1, 2) and (3, 2). Find the co-ordinates of other two vertices.
Solution:
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 111
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 112
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 113

Hope given RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.2 are helpful to complete your math homework.

If you have any doubts, please comment below. Learn Insta try to provide online math tutoring for you.

RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2

RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2

These Solutions are part of RD Sharma Class 10 Solutions. Here we have given RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2

Other Exercises

Question 1.
Find, in terms of π the length of the arc that subtends an angle of 30° at the centre of a circle of radius 4 cm.
Solution:
Radius of the circle (r) = 4 cm
Angle at the centre subtended an arc = 30°
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 1

Question 2.
Find the angle subtended at the centre of a circle of radius 5 cm by an arc of length \((\frac { 5\pi }{ 3 } \) cm.
Solution:
Radius of the circle (r) = 5 cm 571
Length of arc = \(\frac { 5\pi }{ 3 }\) cm
Let θ be the angle subtended by the arc, then
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 2

Question 3.
An arc of length 20tc cm subtends an angle of 144° at the centre of a circle. Find the radius of the circle.
Solution:
Length of an arc = 20π cm
Angle subtended by the arc = 144°
Let r be the radius of the circle, then
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 3

Question 4.
An arc of length 15 cm subtends an angle of 45° at the centre of a circle. Find in terms of π ; the radius of the circle.
Solution:
Length of arc = 15 cm
Angle subtended at the centre = 45°
Let r be the radius of the circle, then
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 4
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 5

Question 5.
Find the angle subtended at the centre of a circle of radius ‘a’  by an arc of length \((\frac { a\pi }{ 4 } )\)  cm.
Solution:
Radius of the circle (r) = a cm
Length of arc = \(\frac { a\pi }{ 4 }\)   cm
Let θ be the angle subtended by the arc at the centre, then
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 6

Question 6.
A sector of a circle of radius 4 cm contains an angle of 30°. Find the area of the sector.
Solution:
Radius of the sector of a circle (r) = 4 cm
Angle at the centre (θ) = 30°
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 7
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 8

Question 7.
A sector of a circle of radius 8 cm contains an angle of 135°. Find the area of the sector.
Solution:
Radius of the sector of the circle (r) = 8 cm
Angle at the centre (θ) = 135°
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 9

Question 8.
The area of a sector of a circle of radius 2 cm is 7 is cm2. Find the angle contained by the sector.
Solution:
Area of the sector of a circle =π cm2
Radius of the circle (r) = 2 cm
Let 0 be the angle at the centre, then
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 10

Question 9.
The area of a sector of a circle of radius 5 cm is 5π cm2. Find the angle contained by the sector.
Solution:
Area of the sector of a circle = 5π cm2
Radius of the circle (r) = 5 cm
Let 9 be the angle at the centre, then
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 11

Question 10.
Find the area of the sector of a circle of radius 5 cm, if the corresponding arc length is 3.5 cm. [NCERT Exemplar]
Solution:
Let the central angle of the sector be θ.
Given that, radius of the sector of a circle (r) = 5 cm
and arc length (l) = 3.5 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 12
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 13

Question 11.
In a circle of radius 35 cm, an arc subtends an angle of 72° at the centre. Find the length of the arc and area of the sector.
Solution:
Radius of the circle (r) = 25 cm
Angle at the centre (θ) = 72°
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 14

Question 12.
The perimeter of a sector of a circle of radius 5.7 m is 27.2 m. Find the area of the sector.
Solution:
Radius of the circle (r) = 5.7 m
Perimeter of the sector = 27.2 m
Length of the arc = Perimeter – 2r
= (27.2 – 2 x 5.7) m
= 27.2 – 11.4 = 15.8 m
Let θ be the central angle, then
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 15
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 16

Question 13.
The perimeter of a certain sector of a circle of radius 5.6 cm is 27.2 m. Find the area of the sector.
Solution:
Radius of the sector (r) = 5.6 cm
and perimeter of the sector = 27.2 cm
∴ Length of arc = Perimeter – 2r
= 27.2 – 2 x 5.6
= 27.2- 11.2= 16.0 cm
∴ θ be the angle at the centre, then
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 17

Question 14.
A sector is cut-off from a circle of radius 21 cm. The angle of the sector is 120°. Find the length of its arc and the area.
Solution:
Radius of the sector of a circle (r) = 21 cm
Angle at the centre = 120°
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 18

Question 15.
The minute hand of a clock is \(\sqrt { 21 } \)  cm long, Find the area described by the minute hand on the face of the clock between 7.00 A.M. and 7.05 A.M.
Solution:
Length of minute hand of a clock (r) = \(\sqrt { 21 }\)  cm
Period = 7 a.m. to 7.05 a.m. 5 minutes
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 19

Question 16.
The minute hand of a clock is 10 cm long. Find the area of the face of the clock described by the minute hand between 8.00 A.M. and 8.25 A.M.
Solution:
Length of minute hand of a clock (r) = 10 cm
Period = 8 A.M. to 8.25 A.M. = 25 minutes
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 20

Question 17.
The sector of 56° cut out from a circle contains area 4.4 cm2, Find the radius of the circle.
Solution:
Area of a sector = 4.4 cm2
Central angle = 56°                                        ‘
Let r be the radius of the sector of the circle, then
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 21

Question 18.
Area of a sector of central angle 200° of a circle s 770²cm. Find the length of the corresponding are of this sector.
Solution:
Let the radius of the sector AOBA be r.
Given that, Central angle of sector AOBA = θ = 200°
and area of the sector AOBA = 770 cm2
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 22
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 23

Question 19.
The length of minute hand of a clock is 5 cm. Find the area swept by the minute hand during the time period 6:05 am and 6:40 am.           [NCERT Exemplar]
Solution:
We know that, in 60 min, minute hand revolving = 360°
In 1 min, minute hand revolving = \(\frac { 360\circ }{ 60\circ }\)

RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 24
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 25

Question 20.
The length of the minute hand of a clock is 14 cm. Find the area swept by the minute hand in 5 minutes. [CBSE 2013]
Solution:
Length of minute hand (r)= 14 cm
Area swept by the minute hand in 5 minutes
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 26

Question 21.
In a circle of radius 21 cm, an arc subtends an angle of 60° at the centre. Find (0 the length of the arc (ii) area of the secter formed by the arc. (Use π = 22/7) [CBSE 2013]
Solution:
Radius of a circle (r) = 21 cm
Angle at the centre = 60°
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 27

Question 22.
From a circular piece of cardboard of radius 3 cm two sectors of 90° have been cut off. Find the perimeter of the remaining portion nearest hundredth centimeters (Take π = 22/7).
Solution:
Radius of the circular piece of cardboard (r) = 3 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 28
∴ Two sectors of 90° each have been cut off
∴ We get a semicular cardboard piece
∴ Perimeter of arc ACB
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 29

Question 23.
The area of a sector is one-twelfth that of the complete circle. Find the angle of the sector.
Solution:
Let r be the radius of the circle and 0 be the central angle of the sector of the circle Then area of circle = πr2

RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 30

Question 24.
AB is a chord of a circle with centre O and radius 4 cm. AB is of length 4 cm. Find the area of the sector of the circle formed by the chord AB.
Solution:
Radius of the circle with centre O (r) = 4 cm
Length of chord AB = 4 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 31

Question 25.
In a circle of radius 6 cm, a chord of length 10 cm makes an angle of 110° at the centre of the circle. Find 
(i)  the circumference of the circle,
(ii) the area of the circle,
(iii) the length of the arc AB,
(iv) the area of the sector OAB.
Solution:
Radius of the circle (r) = 6 cm
Length of chord = 10 cm
and central angle (θ) =110°
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 32
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 33

Question 26.
Figure, shows a sector of a circle, centre O, containing an angle θ°. Prove that :
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 34
Solution:
Radius of the circle = r
Arc AC subtends ∠θ at the centre of the
circle. OAB is a right triangle
In the right ΔOAB,
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 35
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 36
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 37

Question 27.
Figure, shows a sector of a circle of radius r cm containing an angle θ°. The area of the sector is A cm2 and perimeter of the sector is 50 cm. Prove that
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 38
Solution:
Radius of the sector of the circle = r cm
and angle at the centre = 0
Area of sector OAB = A cm2
and perimeter of sector OAB = 50 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 39
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 40

Hope given RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.2 are helpful to complete your math homework.

If you have any doubts, please comment below. Learn Insta try to provide online math tutoring for you.

RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.1

RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.1

These Solutions are part of RD Sharma Class 10 Solutions. Here we have given RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.1

Other Exercises

Question 1.
On which axis do the following points lie?
(i) P (5, 0)
(ii) Q (0 – 2)
(iii) R (-4, 0)
(iv) S (0, 5)
Solution:
(i) P (5, 0)
Its ordinate or y-axis is 0. It lies on x-axis
(ii) Q (0 – 2)
Its abscissa or x-axis is 0. It lies on y-axis
(iii) R (-4, 0)
Its ordinate is 0 It lies on x-axis
(iv) S (0, 5)
Its abscissa is 0. It lies on y-axis

Question 2.
Let ABCD be a square of side 2a. Find the coordinates of the vertices of this square when
(i) A coincides with the origin and AB and AD are along OX and OY respectively.
(ii) The centre of the square is at the-origin and coordinate axes are parallel to the sides AB and AD respectively.
Solution:
ABCD is a square whose side is 2a
(i) A coincides with origin (0, 0)
AB and AD are along OX and OY respectively
Co-ordinates of A are (0, 0), of B are (2a, 0) of C are (2a, 2a) and of D are (0, 2a)
(ii) The centre of the square is at the origin (0, 0) and co-ordinates axes are parallel to the sides AB and AD respectively.
Then the co-ordinates of A are (a, a) of B are (-a, a), of C are (-a, -a) and of D are (a, -a) as shown in the figure given below :
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.1 1

Question 3.
The base PQ of two equilateral triangles PQR and PQR’ with side 2a lies along y- axis such.that the mid-point of PQ is at the origin. Find the coordinates of the vertices R and R’ of the triangles.
Solution:
∆PQR and PQR’ are equilateral triangles with side 2a each and base PQ and mid of point of PQ is 0 (0, 0) and PQ lies along y-axis
RD Sharma Class 10 Solutions Chapter 6 Co-ordinate Geometry Ex 6.1 2

 

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CA Foundation Business Economics Study Material – Supply

CA Foundation Business Economics Study Material Chapter 2 Theory of Demand and Supply – Supply

MEANING

Supply of a commodity refers to the quantity of commodity offered for sale at a particular price during a given period of time. Thus, the supply of a commodity may be defined as the amount of commodity which the sellers or producers are able and willing to offer for sale at a particular price, during a given period of time.

Thus, defined, the term supply shows the following features:

  1. Supply of a commodity is always with reference to a PRICE,
  2. Supply of a commodity is to be referred to IN A GIVEN PERIOD OF TIME.
  3. Supply of a commodity depends on the ABILITY OF SELLER TO SUPPLY A COMMODITY. However, ability of a seller to supply a commodity depends ON THE STOCK available with him.
  4. Supply of a commodity also depends on the WILLINGNESS OF SELLER TO SUPPLY A COMMODITY. A seller’s willingness to supply a commodity depends ON THE DIFFERENCE BETWEEN THE RESERVATION PRICE and the PREVAILING MARKET PRICE.
  5. E.g. A dairy farm’s daily supply of milk at the price of Rs. 12 per litre is 600 litres

Determinants of Supply

Supply of a commodity depends on many factors like price of the commodity, price of related goods, prices of factors of production, technology, etc. All determinants of supply can be expressed in the form of supply function as follows-
S= f(Px, Pr, Pf, T, O …….. )
Where – Sx = Quantity supplied of commodity x
f = function of (depends on)
Px = Price of commodity x
Pr = Price of related commodities
Pf = Prices of factors of production.
T = Technology
O = Objectives/Goals of the firm

Price of the commodity:

  • Other things being equal the supply of a commodity is DIRECTLY related with its price.
  • It means that, larger quantity of a commodity is offered for sale at higher price and vice versa.
  • This is because the profits of the firm increases if the price of its product increases.

Price of the related commodities:

  • The supply of a commodity also depends on the prices of related commodities i.e. substitute goods and complementary goods.
  • Other things being equal, if the price of a substitute goes up, the firms will be tempted to produce that substitute to get higher profits. E.g. – If the price of coffee rises, the firm would reduce the quantity supplied of tea.
  • On the other hand, other things being equal/if price of a complementary good goes up, the supply of the product in question also rises. E.g.- If the prices of fountain pens rise, it may cause an increase in the supply of ink.

Prices of factors of production:

  • Supply of a commodity depends on the cost of production. The cost of production itself depends upon the prices of various factors of production.
  • So, if the price of any factor of production rises, the production costs would be higher for the same level of output (and vice versa), Hence the supply will tend to decrease.
  • Conversely, a fall in the cost of production tends to increase the supply.

State of technology:

  • A change in technology affects the supply of commodity.
  • A technological progress and improvement in the methods of production increases productivity, reduce the cost of production and increases the profits. As a result more is produced and supplied.
  • Also discoveries and innovations bring new variety of goods.

Objectives of the firm:

  • The objectives of the firm and business policy pursued by it also affect the supply of the product produced by it.
  • Some firms believes in higher margin of profits and lower turnover while others believe in lower margin of profit and higher turnover (i.e. sales) to capture the market or to improve status, goodwill and prestige in the market.

Government Policy:

  • The supply of a commodity is also affected by the economic policies followed by the Government.
  • The Government may impose taxes on commodities in the form of excise duty, sales tax and import duties or may give subsidies.
  • Any increase in such taxes will raise the cost of production and so the quantity supplied will fall. Under such conditions supply will increase only when its price in the market rises.
  • Subsidies reduce the cost of production and thus encourages firms to produce and sell more.

Time:

  • Supply is a function of time also.
  • In a short period, it is not possible to adjust supply to the conditions of demand.
  • If the time period is sufficiently long, all possible adjustments can be made in the production apparatus and the supply can be fully adjusted to demand.

Number of firms:
If the number of firms producing a product increases, the market supply of the product will also increase and vice-versa.

Other factors:
Supply of a commodity also depends upon Natural conditions like rainfall, temperature, etc.; industrial and foreign policies, infrastructural facilities; War; market structure; etc.

Law of Supply

  • The Law of Supply express the nature of functional relationship between the price of a commodity and its quantity supplied.
  • It simply states that supply varies DIRECTLY to the changes in price i.e. supply of a commodity expands when price rises and contracts when price falls.
  • “The Law of Supply states that the higher the price, the greater the quantity supplied or the lower the price the smaller the quantity supplied, other things remaining the same.” (Dooley)
  • Thus, there is DIRECT RELATIONSHIP between supply and price.
  • It is assumed that other determinants of supply are constant and ONLY PRICE IS THE VARIABLE AND INFLUENCING FACTOR.

Thus, the law of supply is based on the following main assumptions:-

  • Cost of production remains unchanged even though the price of the commodity changes.
  • The technique of production remains unchanged.
  • Government policies like taxation policy, trade policy, etc. remains unchanged.
  • The prices of related goods remains unchanged.
  • The scale of production remains unchanged etc.

The law can be explained with the help of supply schedule and a corresponding supply curve.

ca-foundation-business-economics-study-material-supply-1

  • The supply schedule shows that when price rises from Rs.10 per unit to Rs. 20 per unit, the supply also rises from 20 units per week to 30 units per week and so on.
  • Thus, it shows a direct relationship between price and quantity supplied other things being equal.
  • A supply curve is the supply schedule depicted on the graph. The supply curve shows the same information as the supply schedule.

ca-foundation-business-economics-study-material-supply-2

  • In the diagram, the supply curve is sloping upwards from left to right showing a direct relationship between the price and quantity supplied.
  • A single point on supply curve show a single price supply relationship E.g. – Point ‘C’ show that if price is Rs. 30, quantity supplied is 40 units.
  • The law of supply states that, supply of a commodity varies directly with its price.

But, in some cases, this may not hold true. Hence, the law of supply has the following EXCEPTIONS.

  1. When the seller expects a further rise in the prices in future, he may hoard stock of commodity. So the supply at present will fall and vice versa.
  2. At higher wage rates, there is tendency among labourers to prefer more leisure than work. As a result when wages rise, labour supply falls.
  3. In the case of rare commodities like paintings, coins, etc. the supply is fixed. Whatever the price, it cannot change.
  4. In an auction or in all those cases where the seller wants to get rid of his goods, he will sell the goods at whatever price they fetch.

Changes in Quantity Supplied OR Expansion & Contraction of supply OR Movement along a supply curve

  • When supply of a commodity changes only due to change in the price of commodity other determinants remaining unchanged, it is called changes in quantity supplied.
  • Changes in quantity supplied thus means -expansion of supply & contraction of supply
  • When price of a commodity rises, quantity supplied also rises. This is called expansion of supply.
  • When price of a commodity falls, quantity supplied also falls. This is called contraction of supply.

As other determinants of supply like price of related commodities, prices of factors of production, state of technology, etc. are assumed to be constant, the position of the supply curve remains the same. The seller will move upwards or downwards on the same supply curve.

ca-foundation-business-economics-study-material-supply-3
In the figure above –

  • At price OP quantity supplied is OQ
  • With a rise in price to OPthe quantity supplied rises from OQ to OQ1 The co-ordinate point moves up from E to E1 This is called ‘a rise in quantity supplied’.
  • With a fall in price to OPthe quantity supplied falls from OQ to OQ2 The co-ordinate point moves down from E to E2 This is called ‘a fall in quantity supplied’.

Changes in supply OR Increase and decrease in Supply OR Shift in Supply curve

  • When there is change in supply due to change ‘ in factors other than price of the commodity, it is called changes in supply.
  • It is the result of change in technology, govt, policies, prices of related goods etc.
  • Change in supply means- increase in supply & decrease in supply.
  • Price remaining the same when supply rises due to change in factors other than price, it is called increase in supply.
  • Likewise, price remaining the same when supply falls due to change in factors other than price, it is called decrease in supply.

In this case the supply curve shifts from its original position to rightward when supply increases and to leftward when supply decreases. Thus, change in supply curve as a result of increase and decrease in supply, is technically called shift in supply curve.

ca-foundation-business-economics-study-material-supply-4
In the figure above-

  • Original supply curve is SS. At OP price, OQ quantity is being supplied.
  • As the supply changes, the supply curve shifts either to the right (S1S1)or to the left (S2S2)
  • At S1S1, OQ1, quantity is being supplied at the price OP. This shows increase in supply. More quantity is being supplied at same price. It is denoted by rightward shift in supply curve.
  • At S2S2, OQ2 quantity is being supplied at the price OP. This shows decrease in supply. Less quantity is being supplied at same price. It is denoted by leftward shift in supply curve.

Elasticity of supply

  • Price elasticity of supply measures the degree of responsiveness of quantity supplied of a commodity to a change in its own price.
  • In other words, the elasticity of supply shows the degree of change in the quantity supplied in response to change in the price of the commodity.
  • Elasticity of supply can be defined “as a ratio of the percentage change in the quantity supplied of a commodity to the percentage change in its own price”.
  • It may be expressed as follows –
    ca-foundation-business-economics-study-material-supply-5
  • Since the law of supply establishes positive relationship between price and quantity supplied, the elasticity of supply would be positive.
  • However, in case of decreasing cost industry elasticity of supply is negative.
  • The value of elasticity co-efficient will vary from zero to infinity.

The elasticity of supply, according to its degree, may be of following types:-

1. Perfectly Inelastic Supply: Es = 0:
When a change in the price of a commodity has no effect on its quantity supplied, then supply is perfectly inelastic.
E.g. – If price rises by 20% and the quantity supplied remains unchanged then Es = 0/20 = 0. In this case, the supply curve is a vertical straight line curve parallel to Y-axis as shown in the figure.
ca-foundation-business-economics-study-material-supply-6
The figure shows that, whatever the price quantity supplied of the commodity remains unchanged at OQ.

2. Perfectly Elastic Supply: (Es = ∞):
When with no change in price or with very little change in price, the supply of a commodity expands or contracts to any extent, the supply is said to be perfectly elastic. In this case, the supply is a horizontal straight line and parallel to X-axis.
ca-foundation-business-economics-study-material-supply-7
The figure shows (Es = ∞) that, at given price supply is ever increasing.

3. Unit Elastic Supply : (Es =1):
When the percentage change in price is equal to percentage change in quantity supplied, then the supply is said to be unit elastic.
E.g. – If price rises by 10% and the supply also rises by 10% then, E= 10/10=1
ca-foundation-business-economics-study-material-supply-8
In this case the straight line supply curve SS when extended will pass through origin.

4. Relatively/More Elastic Supply: (E>1):
When a small change in price leads to big change in quantity supplied, then the supply is said to be relatively or more elastic. E.g. – If price rises by 10% and supply rises by 30% then,
E= 30/10 = 3>1. The coefficient of elasticity would be somewhere between ONE and INFINITY. The elastic supply curve is flatter as shown below-
ca-foundation-business-economics-study-material-supply-9
Supply curve SS is flat suggesting that the supply is more elastic. In this case the supply curve SS when extended will pass through Y-axis.

5. Relatively Inelastic Or Less Elastic Supply: (Es<1).
When a big change in price leads to small change in quantity supplied, then supply is said to relatively inelastic or less elastic.
E.g. – If price rises by 30% and supply rises by 10% then, Es = 10/30 = 1/3 < 1. The coefficient of elasticity would be somewhere between ZERO and ONE. The supply curve in this case has steep slope as shown below –
ca-foundation-business-economics-study-material-supply-10
Supply curve SS is steeply sloped suggesting that supply is less elastic. In this case the supply curve SS when extended will pass through X-axis.

Measurement of Elasticity of Supply

The different methods of measuring price elasticity of supply are:

  1. The Percentage or Ratio or Proportional Method,
  2. The Point or Geometric Method, and
  3. The Arc Method

1. The Percentage Method:
Thus method is based on the definition of elasticity of supply. The coefficient of price elasticity of supply is measured by taking ratio of percentage change in supply to the percentage change in price. Thus, we measure the elasticity by using the following formula-
ca-foundation-business-economics-study-material-supply-11

  • If the coefficient of above ratio is equal to ONE, the supply will be unitary.
  • If the coefficient of above ratio is MORE THAN ONE, the supply is relatively elastic.
  • If the coefficient of above ratio is LESS THAN ONE, the supply is relatively inelastic.

2. The Point Or Geometric Method:
In point elasticity method, we measure elasticity at a given point on a supply curve.
We can measure E at point ‘R’ in the following manner

  • Extend the supply curve ‘S’ towards the extension of X-axis so that it cuts X-axis at T.
  • Draw a perpendicular from ‘R’ cutting X-axis at ‘M’
  • Take the ratio of intercepts MT and OM.
    Es = MT/OM

ca-foundation-business-economics-study-material-supply-12
In the figure MT > OM, elasticity is GREATER THAN ONE.

ca-foundation-business-economics-study-material-supply-13
In the adjoining figure, supply curve when extended meets X-axis to the right of the point of origin so that
Es = MT/OM < 1
i.e. MT<OM and so elasticity is LESS THAN UNITY

ca-foundation-business-economics-study-material-supply-14
In the adjoining figure, supply curve when extended meets X-axis exactly at the point of origin so that
Es = MT/OM = 1,
i.e. MT = OM and so elasticity of supply is EQUAL TO UNITY/ONE.

3. The Arc Elasticity Method:
Under this method we measure elasticity of supply over an ARC of the supply curve. The arc elasticity is a measured of the “average elasticity” i.e. elasticity at MID-POINT that connects the two points on the supply curve. Thus, an arc is a portion of a curved line, hence a portion of supply curve. The formula used is
ca-foundation-business-economics-study-material-supply-15

Equilibrium Price

  • Equilibrium means a market situation where the quantity demanded is equal to quantity supplied. Thus, the two factors determining equilibrium price are market demand and market supply.
  • Equilibrium price is the price at which the sellers of a good are willing to sell the quantity which buyers want to buy. Thus, equilibrium price (also called market clearing price) is the price at which demand and supply are equal.
  • At equilibrium price both sellers and buyers are satisfied.
  • At equilibrium price, there is neither SHORTAGE nor SURPLUS. So at equilibrium price, market is said to be CLEARED.

The following table and figure explains the equilibrium price.
ca-foundation-business-economics-study-material-supply-16
ca-foundation-business-economics-study-material-supply-17

  • Equilibrium is struck a point E where the demand and supply curve intersect each other.
  • At E, equilibrium price is OP i.e. Rs. 3 and equilibrium quantity is OQ ie. 300 units.
  • When the price is Rs. 5 per unit, the quantity demanded is 100 units and quantity supplies is 500 units. It is situation where market demand < market supply and there is excess supply i.e., surplus supply. At a given price, sellers are willing to sell more than what buyers are ready to buy. As a result of pressure of excess supply the market price falls to Rs. 4.
  • At a price of Rs. 4, the pressure of excess supply still continues and hence the price falls further to Rs. 3.
  • At a price of Rs. 3, the market is CLEARED as the quantity demanded and supplied are equal to each other. There, is no SURPLUS.
  • Thus, we can conclude that pressure of excess supply (surplus) reduces the price.
  • Similarly, if the price is Rs. 1, the quantity demanded is 500 units and quantity supplied is 100 units. It is a situation where market demand > market supply and there is excess demand or SHORTAGE of supply. As a result of excess demand or SHORTAGE of supply the market price will rise. So long as pressure of excess demand continues price will rise i.e. till point E. At point E, excess demand is eliminated and quantity demand and supplied are equal to each other. The market has CLEARED.
  • Thus, we can conclude that pressure of excess demand (shortage of supply) increases the price.
  • The equilibrium price is determined by the intersection between demand and supply therefore, it is also called as the MARKET EQUILIBRIUM.

 

RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1

RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1

These Solutions are part of RD Sharma Class 10 Solutions. Here we have given RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1

Other Exercises

Question 1.
Find the circumference and area of a circle of radius 4.2 cm.
Solution:
Radius of a circle = 4.2 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 1

Question 2.
Find the circumference of a circle whose area is 301.84 cm2.
Solution:
Area of a circle = 301.84 cm2
Let r be the radius, then πr2 = 301.84
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 2

Question 3.
Find the area of a circle whose circum­ference is 44 cm.
Solution:
Circumference of a circle = 44 cm
Let r be the radius,
then 2πr = circumference
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 3

Question 4.
The circumference of a circle exceeds the diameter by 16.8 cm. Find the circum­ference of the circle. (C.B.S.E. 1996)
Solution:
Let r be the radius of the circle
∴  Circumference = 2r + 16.8 cm
⇒  2πr = 2r + 16.8
⇒  2πr – 2r = 16.8
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 4

Question 5.
A horse is tied to a pole with 28 m long string. Find the area where the horse can graze. (Take π = 22/7)
Solution:
Radius of the circle (r) = Length of the rope = 28 m .
Area of the place where the horse can graze
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 5

Question 6.
A steel wire when bent in the form of a square encloses an area of 121 cm2. If the same wire is bent in the form of a circle, find the area of the circle.  (C.B.S.E. 1997)
Solution:
Area of square formed by a wire =121 cm2
∴ Side of square (a) = \(\sqrt { Area } \)  = \(\sqrt { 121 } \)  = 11 cm Perimeter of the square = 4 x side = 4 x 11 = 44 cm
∴Circumference of the circle formed by the wire = 44cm
Let r be the radius
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 6

Question 7.
The circumference of two circles are in the ratio 2 : 3. Find the ratio of their areas.
Solution:
Let R and r be the radii of two circles and their ratio between them circumference = 2 : 3
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 7

Question 8.
The sum of radii of two circles is 140 cm and the difference of their circum­ferences is 88 cm. Find the diameters of the circles.
Solution:
Let R and r be the radii of two circles Then R + r = 140 cm  …….(i)
and difference of their circumferences
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 8
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 9

Question 9.
Find the radius of a circle whose circumference is equal to the sum of the circumferences of two circles of radii 15 cm and 18 cm. [NCERT Exemplar]
Solution:
Let the radius of a circle be r.
Circumference of a circle = 2πr
Let the radii of two circles are r1 and r2 whose
values are 15 cm and 18 cm respectively.
i.e., r1 = 15 cm and r2 = 18 cm
Now, by given condition,
Circumference of circle = Circumference of first circle + Circumference of second circle
⇒   2πr = 2π r1 + 2πr2 =
⇒  r = r1 + r2
⇒   r = 15 + 18
∴ r = 33 cm
Hence, required radius of a circle is 33 cm.

Question 10.
The radii of two circles are 8 cm and 6 cm respectively. Find the radius of the circle having its area equal to the sum of the areas of the two circles.
Solution:
Radius of first circle (r1) = 8 cm
and radius of second circle (r2) = 6 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 10
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 11

Question 11.
The radii of two circles are 19 cm and 9 cm respectively. Find the radius and area of the circle which has its circumference equal to the sum of the circumferences of the two circles.
Solution:
Radius of the first circle (r1) = 19 cm
and radius of the second circle (r2) = 9 cm S
um of their circumferences = 2πr1 + 2πr2
= 2π (r+ r2) = 2π (19 + 9) cm
= 2π x 28 = 56π cm
Let R be the radius of the circle whose circumference is the sum of the circum­ferences of given two circles, then
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 12

Question 12.
The area of a circular playground is 22176 m2. Find the cost of fencing this ground at the rate of ₹50 per metre.  [NCERT Exempiar]
Solution:
Given, area of a circular playground  = 22176 m2
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 13
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 14

Question 13.
The side of a square is 10 cm. Find the area of circumscribed and inscribed circles.
Solution:
ABCD is a square whose each side is 10 cm
∴  AB = BC = CD = DA = 10 cm
AC and BD are its diagonals
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 15
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 16

Question 14.
If a square is inscribed in a circle, find the ratio of the areas of the circle and the square.
Solution:
Let r be the radius of the circle a be the side of the square
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 17
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 18

Question 15.
The area of a circle inscribed in an equilateral triangle is 154 cm2. Find the perimeter of the triangle. (Use π = 22/7 and \(\sqrt { 3 } \)  = 1.73)
Solution:
Area of the inscribed circle of ΔABC = 154 cm2
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 19
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 20

Question 16.
A field is in the form of a circle. A fence is to be erected around the field. The cost of fencing would be ₹2640 at the rate of ₹12 per metre. Then, the field is to be thoroughly ploughed at the cost of ₹0.50 per m2. What is the amount required to plough the field ? (Take π = 22/7)
Solution:
Cost of the fencing the circular field = ₹2640
Rate = ₹12 per metre 2640
∴ Circumference = \((\frac { 2640 }{ 12 } )\) = 220 m
Let r be the radius of the field, then = 2πr = 220
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 21

Question 17.
A park is in the form of a rectangle 120 m x 100 m. At the centre of the park there is a circular lawn. The area of park excluding lawn is 8700 m2. Find the radius of the circular lawn. (Use π = 22/7).
Solution:
Area of the park excluding lawn = 8700 m2
Length of rectangular park = 120 m
and width = 100 m
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 22
∴ Area of lawn = l x b
= 120 x 100 m2 = 12000 m2
Let r be the radius of the circular lawn, then area of lawn = πr2
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 23

Question 18.
A car travels 1 kilometre distance in which each wheel makes 450 complete revolutions. Find the radius of the its wheels.
Solution:
Distance covered by the car in 450 revolutions = 1 km = 1000 m
∴ Distance covered in 1 revolution = \((\frac { 1000 }{ 450 } )\)
= \((\frac { 20 }{ 9 } )\) m
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 24

Question 19.
The area of enclosed between the concentric circles is 770 cm2. If the radius of the outer circle is 21 cm, find the radius of the inner circle.
Solution:
Area of enclosed between two concentric circles = 770 cm2
Radius of the outer circle (R) = 21 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 25

Question 20.
An archery target has three regions formed by the concentric circles as shown in the figure. If the diameters of the concentric circles are in the ratio 1:2:3, then find the ratio of the areas of three regions.[NCERT Exemplar]
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 26
Solution:
Let the diameters of concentric circles be k, 2k , 3k
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 27

Question 21.
The wheel of a motor cycle is of radius 35 cm. How many revolutions per minute must the wheel make so as to keep a speed of 66 km/hr? [NCERT Exemplar]
Solution:
Given, radius of wheel, r = 35 cm
Circumference of the wheel = 2πr
= 2 x \((\frac { 22 }{ 7 } )\) x 35 = 220 cm
But speed of the wheel = 66 kmh-1
= \((\frac { 66 x 1000 }{ 60 } )\) m/ mm
= 1100 x 100 cm min-1
= 110000 cm min-1
∴ Number of revolutions in 1 min
= \((\frac { 110000 }{ 220 } )\)= 500 revolution
Hence, required number of revolutions per minute is 500.

Question 22.
A circular pond is 17.5 m in diameter. It is surrounded by a 2 m wide path. Find the cost of constructing the path at the rate of ₹25 per m2. [NCERT Exemplar]
Solution:
Given that, a circular pond is surrounded by a wide path.
The diameter of circular pond = 17.5 m
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 28

Question 23.
A circular park is surrounded by a rod 21 m wide. If the radius of the park is 105 m, find the area of the road. [NCERT Exemplar]
Solution:
Given that, a circular park is surrounded by a road.
Width of the road = 21 m
Radius of the park (r1) = 105 m
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 29
.’. Radius of whole circular portion (park + road),
re = 105 + 21 = 126 m
Now, area of road = Area of whole circular portion – Area of circular park
= πr2 – πr2             [∵ area of circle = πr2]
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 30

Question 24.
A square of diagonal 8 cm is inscribed in a circle. Find the area of the region lying outside the circle and inside the square.  [NCERT Exemplar]
Solution:
Let the side of a square be a and the radius of circle be r.
Given that, length of diagonal of square = 8 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 31

Question 25.
A path of 4 m width runs round a semi­circular grassy plot whose circumference is 81 \((\frac { 5 }{ 7 } )\)m. Find:
(i) the area of the path
(ii) the cost of gravelling the path at the rate of ₹1.50 per square metre
(iii) the cost of turfing the plot at the rate of 45 paise per m2.
Solution:
Width of path around the semicircular grassy plot = 4 m
Circumference of the plot = 81 \((\frac { 5 }{ 7 } )\)m
= \((\frac { 572 }{ 7 } )\) m
Let r be the radius of the plot, then
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 32
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 33

Question 26.
Find the area enclosed between two concentric circles of radii 3.5 cm and 7 cm. A third concentric circle is drawn outside the 7 cm circle, such that the area enclosed between it and the 7 cm circle is same as that between the two inner circles. Find the radius of the third circle correct to one decimal place.
Solution:
Radius of first circle (r1) = 3.5 cm
Radius of second circle (r2) = 7 cm
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 34
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 35

Question 27.
A path of width 3.5 m runs around a semi­circular grassy plot whose perimeter is 72 m. Find the area of the path. (Use π = 22/7)                   [CBSE 2015]
Solution:
Perimeter of semicircle grassy plot = 72 m
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 36
Let r be the radius of the plot
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 37
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 37.1

Question 28.
A circular pond is of diameter 17.5 m. It is surrounded by a 2 m wide path. Find the cost of constructing the path at the rate of ₹25 per square metre (Use π = 3.14)               [CBSE 2014]
Solution:
Diameter of circular pond (d) = 17.5 m
Radius (r) =\((\frac { 1725 }{ 2 } )\) = 8.75 m
Width of path = 2m
∴  Radius of outer cirlce (R) = 8.75 + 2 = 10.75 m
Area of path = (R2 – r2
= [(10.75)2 – (8.75)2](3.14)
= 3.14(10.75 + 8.75) (10.75 – 8.75)
= 3.14 x 19.5 x 2 = 122.46 m2
Cost of 1 m2 for constructing the path ₹25 m2
∴  Total cost = ₹ 122.46 x 25 = ₹3061.50

Question 29.
The outer circumference of a circular race-track is 528 m. The track is every­where 14 m wide. Calculate the cost of levelling the track at the rate of 50 paise per square metre (Use π= 22/7).
Solution:
Let R and r be the radii of the outer and inner of track.
Outer circumference of the race track = 528 m
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 38
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 39

Question 30.
A road which is 7 m wide surrounds a circular park whose circumference is 352 m. Find the area of the road.
Solution:
Width of the road = 7 m
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 40
Circumference of the park = 352 m
Let r be the radius, then 2πr = 352
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 41
RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 42

Question 31.
Prove that the area of a circular path of uniform width surrounding a circular region of radius r is πh(2r + h).
Solution:
Radius of inner circle = r
Width of path = h
∴ Outer radius (R) = (r + h)
∴ Area of path = πR2 – πr2
= π {(r + h)2 – r2}
= π {r2 + h2 + 2rh – r2}
= π {2rh + h2}
= πh (2r + h) Hence proved.

Hope given RD Sharma Class 10 Solutions Chapter 13 Areas Related to Circles Ex 13.1 are helpful to complete your math homework.

If you have any doubts, please comment below. Learn Insta try to provide online math tutoring for you.

RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS

RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS

These Solutions are part of RD Sharma Class 10 Solutions. Here we have given RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS

Other Exercises

Mark the correct alternative in each of the following :
Question 1.
If 7th and 13th terms of an A.P. be 34 and 64 respectively, then its 18th term is
(a) 87
(b) 88
(c) 89
(d) 90
Solution:
(c) 7th term (a7) = a + 6d = 34
13th term (a13) = a + 12d = 64
Subtracting, 6d = 30 => d = 5
and a + 12 x 5 = 64 => a + 60 = 64 => a = 64 – 60 = 4
18th term (a18) = a + 17d = 4 + 17 x 5 = 4 + 85 = 89

Question 2.
If the sum of p terms of an A.P. is q and the sum of q terms is p, then the sum of (p + q) terms will be
(a) 0
(b) p – q
(c) p + q
(d) – (p + q)
Solution:
(d)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 1

Question 3.
If the sum of n terms of an A.P. be 3n2 + n and its common difference is 6, then its first term is
(a) 2
(b) 3
(c) 1
(d) 4
Solution:
(d)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 2

Question 4.
The first and last terms of an A.P. are 1 and 11. If the sum of its terms is 36, then the number of terms will be
(a) 5
(b) 6
(c) 7
(d) 8
Solution:
(b) First term of an A.P. (a) = 1
Last term (l) = 11
and sum of its terms = 36
Let n be the number of terms and d be the common difference, then
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 3

Question 5.
If the sum of n terms of an A.P. is 3n2 + 5n then which of its terms is 164 ?
(a) 26th
(b) 27th
(c) 28th
(d) none of these
Solution:
(b)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 4

Question 6.
If the sum of it terms of an A.P. is 2n2 + 5n, then its nth term is
(a) 4n – 3
(b) 3n – 4
(c) 4n + 3
(d) 3n + 4
Solution:
(c)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 5

Question 7.
If the sum of three consecutive terms of an increasing A.P. is 51 and the product of the first and third of these terms is 273, then the third term is :
(a) 13
(b) 9
(c) 21
(d) 17
Solution:
(c)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 6

Question 8.
If four numbers in A.P. are such that their sum is 50 and the greatest number is 4 times the least, then the numbers are
(a) 5, 10, 15, 20
(b) 4, 10, 16, 22
(c) 3, 7, 11, 15
(d) None of these
Solution:
(a)
4 numbers are in A.P.
Let the numbers be
a – 3d, a – d, a + d, a + 3d
Where a is the first term and 2d is the common difference
Now their sum = 50
a – 3d + a – d + a + d + a + 3d = 50
and greatest number is 4 times the least number
a + 3d = 4 (a – 3d)
a + 3d = 4a – 12d
4a – a = 3d + 12d
=> 3a = 15d
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 7

Question 9.
Let S denotes the sum of n terms of an A.P. whose first term is a. If the common difference d is given by d = Sn – k Sn-1 + Sn-2 then k =
(a) 1
(b) 2
(c) 3
(d) None of these
Solution:
(b)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 8

Question 10.
The first and last term of an A.P. are a and l respectively. If S is the sum of all the terms of the A.P. and the common difference is given by
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 9
(a) S
(b) 2S
(c) 3S
(d) None of these
Solution:
(b)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 10

Question 11.
If the sum of first n even natural number is equal to k times the sum of first n odd natural numbers, then k =
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 11
Solution:
(d)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 12

Question 12.
If the first, second and last term of an A.P. are a, b and 2a respectively, its sum is
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 13
Solution:
(c)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 14

Question 13.
If S1 is the sum of an arithmetic progression of ‘n’ odd number of terms and S2 is the sum of the terms of the
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 15
Solution:
(a)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 16
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 17

Question 14.
If in an A.P., Sn = n2p and Sm = m2p, where S denotes the sum of r terms of the A.P., then Sp is equal to
(a) \(\frac { 1 }{ 2 }\) p3
(b) mnp
(c) p3
(d) (m + n) p2
Solution:
(c)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 18

Question 15.
If Sn denote the sum of the first n terms of an A.P. If S2n = 3Sn , then S3n : Sn is equal to
(a) 4
(b) 6
(c) 8
(d) 10
Solution:
(b)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 19

Question 16.
In an AP, Sp = q, Sq = p and S denotes the sum of first r terms. Then, Sp+q is equal to
(a) 0
(b) – (p + q)
(c) p + q
(d) pq
Solution:
(c) In an A.P. Sp = q, Sq = p
Sp+q = Sum of (p + q) terms = Sum of p term + Sum of q terms = q + p

Question 17.
If Sn denotes the sum of the first r terms of an A.P. Then, S3n : (S2n – Sn) is
(a) n
(b) 3n
(b) 3
(d) None of these
Solution:
(c)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 20

Question 18.
If the first term of an A.P. is 2 and common difference is 4, then the sum of its 40 term is
(a) 3200
(b) 1600
(c) 200
(d) 2800
Solution:
(a)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 21

Question 19.
The number of terms of the A.P. 3, 7,11, 15, … to be taken so that the sum is 406 is
(a) 5
(b) 10
(c) 12
(d) 14
Solution:
(d)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 22

Question 20.
Sum of n terms of the series
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 23
Solution:
(c)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 24
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 25

Question 21.
The 9th term of an A.P. is 449 and 449th term is 9. The term which is equal to zero is
(a) 50th
(b) 502th
(c) 508th
(d) None of these
Solution:
(d)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 26

Question 22.
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 27
Solution:
(c)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 28
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 29

Question 23.
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 30
Solution:
(b) Sn is the sum of first n terms
Last term nth term = Sn – Sn-1

Question 24.
The common difference of an A.P., the sum of whose n terms is Sn, is
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 31
Solution:
(a)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 32

Question 25.
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 33
Solution:
(b)
In first A.P. let its first term be a1 and common difference d1
and in second A.P., first term be a2 and common difference d2, then
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 34

Question 26.
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 35
Solution:
(b)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 36
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 37

Question 27.
If the first term of an A.P. is a and nth term is b, then its common difference is
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 38
Solution:
(b)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 39

Question 28.
The sum of first n odd natural numbers is
(a) 2n – 1
(b) 2n + 1
(c) n2
(d) n2 – 1
Solution:
(c)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 40

Question 29.
Two A.P.’s have the same common difference. The first term of one of these is 8 and that of the other is 3. The difference between their 30th terms is
(a) 11
(b) 3
(c) 8
(d) 5
Solution:
(d) In two A.P.’s common-difference is same
Let A and a are two A.P. ’s
First term of A is 8 and first term of a is 3
A30 – a30 = 8 + (30 – 1) d – 3 – (30 – 1) d
= 5 + 29d – 29d = 5

Question 30.
If 18, a, b – 3 are in A.P., the a + b =
(a) 19
(b) 7
(c) 11
(d) 15
Solution:
(d) 18, a, b – 3 are in A.P., then a – 18 = -3 – b
=> a + b = -3 + 18 = 15

Question 31.
The sum of n terms of two A.P.’s are in the ratio 5n + 4 : 9n + 6. Then, the ratio of their 18th term is
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 41
Solution:
(a)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 42
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 43

Question 32.
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 44
Solution:
(b)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 45
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 46

Question 33.
The sum of n terms of an A.P. is 3n2 + 5n, then 164 is its
(a) 24th term
(b) 27th term
(c) 26th term
(d) 25th term
Solution:
(b)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 47

Question 34.
If the nth term of an A.P. is 2n + 1, then the sum of first n terms of the A.P. is
(a) n (n – 2)
(b) n (n + 2)
(c) n (n + 1)
(d) n (n – 1)
Solution:
(b)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 48

Question 35.
If 18th and 11th term of an A.P. are in the ratio 3 : 2, then its 21st and 5th terms are in the ratio
(a) 3 : 2
(b) 3 : 1
(c) 1 : 3
(d) 2 : 3
Solution:
(b)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 49

Question 36.
The sum of first 20 odd natural numbers is
(a) 100
(b) 210
(c) 400
(d) 420 [CBSE 2012]
Solution:
(c)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 50

Question 37.
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 51
Solution:
(a)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 52

Question 38.
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 53
Solution:
(c)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 54

Question 39.
The common difference of the A.P. \(\frac { 1 }{ 2b }\) ,
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 55
Solution:
(d)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 56

Question 40.
If k, 2k – 1 and 2k + 1 are three consecutive terms of an AP, the value of k is
(a) -2
(b) 3
(c) -3
(d) 6 [CBSE 2014]
Solution:
(b) (2k – 1) – k = (2k + 1) – (2k- 1)
2k – 1 – k = 2
=> k = 3

Question 41.
The next term of the A.P. , √7 , √28, √63, …………
(a) √70
(b) √84
(c) √97
(d) √112 [CBSE 2014]
Solution:
(d)
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS 57
= √(l6 x 7)= √112

Question 42.
The first three terms of an A.P. respectively are 3y – 1, 3y + 5 and 5y + 1. Then, y equals
(a) -3
(b) 4
(c) 5
(d) 2 [CBSE 2014]
Solution:
(c) 2 (3y + 5) = 3y – 1 + 5y + 1
(If a, b, c are in A.P., b – a = c – b=> 2b = a + c)
=> 6y + 10 = 8y
=> 10 = 2y
=> y = 5

Hope given RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions MCQS are helpful to complete your math homework.

If you have any doubts, please comment below. Learn Insta try to provide online math tutoring for you.

CA Foundation Business Economics Study Material – Theory of Consumer Behaviour

CA Foundation Business Economics Study Material Chapter 2 Theory of Demand and Supply – Theory of Consumer Behaviour

Theory of Consumer Behaviour

NATURE OF HUMAN WANTS

All wish, desires, tastes and motives of human beings are called wants in Economics. Human wants show some well marked characteristics as follows-

  • Wants are unlimited
  • Particular want is satiable
  • Wants are complementary
  • Wants are competitive
  • Some wants are both complementary and competitive
  • Wants are alternative
  • Wants vary with time, place, and person
  • Wants vary in urgency and intensity
  • Wants recur
  • Wants are influenced by advertisement
  • Wants become habits and customs
  • Present wants appear to be more important than future wants

Classification of wants:

1. Necessaries:

  • Necessaries of existence – These are the things without which we cannot exist. E.g. minimum of food, clothing and shelter.
  • Necessaries of Efficiency – These are the things which are not necessary to enable us to live, but are necessary to make us efficient workers and to take up any productive activities.
  • Conventional Necessaries – These are the things which are needed either because of social custom or traditions and because the people around us expect us to so.

2. Comforts:
Those goods and services which make for a fuller life and happy life are called comforts. E.g. for a student book is a necessity, a table and a chair are necessaries of efficiency, but cushioned chair is comfort.

3. Luxuries:
Luxuries are those wants which are superfluous and expensive. They are something we could easily do without. E.g. jewellery, big house, luxurious car, dining in a five star hotel etc.

What is Utility?

  • The demand of a commodity depends on the utility of that commodity to a consumer.
  • The want satisfying capacity or power of a commodity is called utility. It is anticipated satisfaction by a consumer.
  • It is a subjective and relative term and varies from person to person, place to place and time
    to time.
  • Utility does not mean the same things as usefulness. E.g. Liquor, Cigarettes, etc. have utility as people are ready to buy them but they are harmful for the health.
  • Therefore, utility has no moral or ethical significance.
  • To study the consumer behaviour, the two important theories are –
    – Marginal utility analysis, given by Dr. Alfred Marshall, and
    – Indifference curve analysis given by Hicks and Allen.

Marginal Utility Analysis

  • The theory of Marginal utility Analysis of demand was given by Alfred Marshall, a British economist.
  • He explained how a consumer spends his money income on different goods and services in order to get maximum satisfaction ie. how a consumer reaches equilibrium.
  • Dr. Alfred Marshall assumes that the utility derived from the consumption of a commodity is measurable. Hence, this approach is called CARDINAL APPROACH.

Marginal utility Analysis is based on the following assumptions:-

  • The Cardinal Measurability of utility: According to this theory, utility is a cardinal concept, ie. it is possible to measure and quantify satisfaction derived from the consumption of various commodities. According to Marshall, money is the measuring rod of marginal utility. E.g. – If a person is ready to pay Rs. 10 for pastry and Rs. 6 for burger, we can say that price represents the utility which he is expecting from these commodities.
  • Constancy of the Marginal Utility of Money: The marginal utility of money remain constant during the time when the consumer is spending money on a good and as a result of which the amount of money is reducing. This is so because money is used as a measuring rod of utility. If the money which is a unit of measurement itself varies, it cannot give correct measurement of the marginal utility of a good.
  • Independent Utilities: According to this assumption, the amount of utility which a consumer gets from one commodity, does not depend upon the quantity of other commodities consumed. E.g. – If a person is consuming Rooh Hafza Sharbat, its utility is not affected by the availability of sugar or Rose Sharbat. It just depends upon the availability of Rooh Hafza Sharbat only. This assumption, in other words, totally ignores the presence of complementary and substitute goods.
  • Rationality: The consumer is assumed to be rational whose aim is to maximise his utility subject to the constraint imposed by his given income. He makes all calculations
    carefully and then purchases the commodities.

The Law of Diminishing Marginal Utility

The Law of Diminishing Marginal Utility is based on two important facts, namely:
(a) Human wants are unlimited
(b) Each separate human want is limited. The amount of any commodity which a man can consume, in a given period of time is limited and hence each single want is satiable.

The law describes that, as the consumer has more and more of a commodity, the additional utility which he derives from an additional unit of commodity goes on falling. Marshall stated the law as follows

“The additional benefit which a person derives from a given increase in stock of a thing diminishes with every increase in the stock that he already has.” The law can be explained with the help of following table:

ca-foundation-business-economics-study-material-theory-of-consumer-behaviour-1

  • The above table shows that as the consumer goes on consuming rossgullas, the additional or marginal utility goes on diminishing.
  • The consumption of 3rd unit of rossgulla gives no additional utility and the 4th unit is giving negative utility.
  • The 4th unit instead of giving satisfaction causes dissatisfaction.
  • Total utility goes on increasing as long as MU is positive, but at diminishing rate.
  • When total utility is highest, marginal utility is zero. This is the point of full satisfaction.
  • When marginal utility becomes negative, total utility starts falling.
  • MU is the rate of change in TU or slope of TU curve.
  • MU can be positive, zero or negative.

We can show the information given in the table on a graph as follows:-
The figure shows that marginal utility curve goes on declining as the consumption increases. It even crosses the X-axis and suggest negative marginal utility. Total utility curve rises upto a point and then starts falling.ca-foundation-business-economics-study-material-theory-of-consumer-behaviour-2

The Law of Diminishing Marginal Utility helps us to understand how a consumer reaches equilibrium in ONE COMMODITY CASE.

  • A consumer tries to equalize marginal utility of a commodity with its price in order to maximize the satisfaction. A consumer thus compares the price with the marginal utility of a commodity.
  • He keep on purchasing a commodity till MU > P. In other words, so long as price is less, he buys more which is also the basis of the law of demand.
  • The consumer is at equilibrium where:
    Marginal Utility of the commodity = Price of the commodity
    ca-foundation-business-economics-study-material-theory-of-consumer-behaviour-3

In reality, a consumer spends his money income to buy different commodities. In case of many commodities, consumer equilibrium is explained with the Law of Equi-Marginal Utility.

  • The law states that a consumer will allocate his expenditure in a way that the utility gained from the last rupee spent on each commodity is equal or the marginal utility each commodity is proportional to its price.
  • The consumer is said to be equilibrium when the following condition is met-
    ca-foundation-business-economics-study-material-theory-of-consumer-behaviour-4

The Law of Diminishing Marginal Utility is based on the following assumptions:-

  1. Homogeneous Units:
    It is assumed that all the units of the commodity are homogeneous ie. identical in every respect like size, taste, colour, quality, blend, etc.
    E.g. – If a consumer is consuming CADBURY DAIRY MILK CHOCOLATE (40 gms.), then all bars of chocolate must be of Dairy Milk Chocolates and not of any other type.
  2. Continuous Consumption:
    There should not be any time gap or interval between the consumption of one unit and another unit.
  3. Rationality:
    The consumer is assumed to be rational.
  4. Cardinal Measurement:
    The utility is measurable and quantifiable.
  5. Constancy of Marginal Utility of Money:
    The marginal utility of money remain unchanged throughout when the consumer is spending on a commodity.
  6. The tastes of consumers should remain constant.

Exceptions to and limitations of the Law of Diminishing Marginal Utility:
In some cases a consumer gets increasing marginal utility with the increase in consumption.
Such cases are called as exception which are as follows-

  1. Hobbies and Rare Collections: The law does not hold good in case of hobbies and rare collections like reading, collection of stamps, coins, etc. Every additional unit gives more satisfaction ie. the marginal utility tends to increase.
  2. Abnormal Persons: The law does not apply to abnormal persons like misers, drunkards, musicians, drug addicts, etc. who want more and more of the commodity they are in love with.
  3. Indivisible Goods: The law cannot be applied in case of indivisible bulky goods like T. V. set, house, scooter, etc. No one purchases more than one unit of such goods at a time.

The limitations of the Law of Diminishing Marginal Utility are as follows –

  1. Cardinal Measurement Unrealistic: The law assumes cardinal measurement of utility. This is unrealistic, because, utility being a subjective or psychological phenomenon, cannot be measured numerically. The feeling experienced by a consumer cannot be quantified.
  2. Unrealistic Conditions: The law is based on unrealistic assumptions. It is not possible to meet all conditions like homogeneous goods, continuous consumption, rationality, etc. at the same time.
  3. Constant Marginal Utility of Money: The law assumes that marginal utility of money remains constant. Therefore, the utility of the commodity depends on its quantity alone. But, the marginal utility of money never remains constant.
  4. Inapplicable to Indivisible Goods: The assumptions of the Law of DMU cannot be made applicable to indivisible bulky goods like T. V. Sets, scooter, house, etc. because no one purchases more than one unit of such goods at a time.
  5. Single Commodity Model: The Law of DMU is a single commodity model. Marginal utility of each commodity is measured independently. But, a consumer may purchase more than one commodity. Also, utilities of goods such as complementary or substitutes are interdependent.

Consumer’s surplus

Consumers Surplus is one of the important concept in economic theory and in economic policy making. It was given by Dr. Alfred Marshall. Marshall’s concept of consumer surplus is based on the following assumptions:

  • Utility can be cardinally measured in monetary units.
  • Marginal utility of money remains constant.
  • Income, fashion and taste of consumer remains constant.
  • Independent marginal utility of each unit of the commodity. .
  • The law of diminishing marginal utility holds good.

EXPLANATION-

  • In our daily expenditure, we often find that the price we pay for a commodity is less than the satisfaction derived from its consumption.
  • Therefore, we are ready to pay much higher price for a commodity than we actually have to pay.
    E.g. Commodities like salt, newspaper, match box, etc. are very useful, but they are also very cheap.
  • From the purchase of such commodities we derive a good deal of extra satisfaction or surplus over and above the price that we pay for them. This is consumer’s surplus.
  • Marshall defined consumer surplus “as the excess of the price which a person would be willing to pay rather than go without the thing over that which he actually does pay”.
  • Thus, it is the difference between what a consumer is ready to pay and what he actually pays.
    Consumer Surplus = What a consumer is ready to pay – What he actually pays = Sum of Marginal Utilities – (Price X Units Purchased)
    = Total Utility – Total amount spent.

We can illustrate the concept of consumer’s surplus with the help of following table-

ca-foundation-business-economics-study-material-theory-of-consumer-behaviour-5

When the consumer buy first unit of commodity he is ready to pay Rs. 25 for it as he expects satisfaction worth Rs. 25 from it and thus gets a surplus worth Rs. 15. For second unit he is ready to pay only Rs. 20 for it as he expects lesser satisfaction from it and thus gets surplus worth Rs. 10 only. The consumer will go on buying the commodity till Marginal Utility = Price & consumer surplus is Zero i.e. upto 4th unit.
Here, Consumer Surplus = Total Utility – Total Amt. Spent = Rs. 70 – Rs. 40 = Rs. 30.
We can represent consumers surplus with the following diagram.

ca-foundation-business-economics-study-material-theory-of-consumer-behaviour-6
In the diagram MU is the marginal utility curve. OP (Rs. 10) is the market price. In equilibrium, consumer would buy OQ (4) units (at this MU = P). For OQ (4) units he is required to pay OQ (4 units) X OP (Rs. 10) = OQSP(Rs. 40). The consumer was ready to pay (by MU curve) OQ SA(Rs. 70). Thus, he derives surplus of satisfaction. OQSA(Rs. 70) – OQSP(Rs. 40) = PSA(Rs. 30)

The uses/importance of the consumer surplus concept are as follows:-

1. Distinction between Value-in-Useand Value-in-exchange: Consumer’s surplus draws a clear distinction between value-in-use and value-in-exchange. E.g. – SALT have great value -in-use but much less value-in-exchange. Being necessity and cheap thing, it yield a large consumer surplus. The consumer’s surplus depends on total utility, whereas price depends on marginal utility. The total utility of salt consumed is much greater but its marginal utility (and price) is low due to its excess supply.

2. Comparing Advantages of Different Places: The concept of consumer’s surplus is useful when we compare the advantages of living in two different places. A place with greater amenities available at cheaper rates give large surplus of satisfaction to consumers than backward place or region. Consumer’s surplus thus indicates conjunctural advantages, Le. the advantages of environment arid opportunities.

3. To the Businessman and Monopolist: A businessman can raise prices of those goods in which there is a large consumer’s surplus. The seller will be able raise price especially if he is a monopolist and controls the supply of the commodity.

4. Useful to the government in determining taxes: The concept is very useful to Finance Minister in imposing taxes on various goods and fixing their rates. He will tax those goods in which the consumers enjoy large surplus. The consumers thus will have to pay more and their consumer’s surplus will fall. But at the same time it will raise the revenue of the government. The loss of consumers must be compared with the gains to the government. If the loss of consumers is greater than the gains to government, then, the tax is not proper and vice versa.

5. Measuring Benefits from International Trade: Through international trade, a country can import goods cheaply le. a country can get goods at lower price than they are prepared to pay for them. The imports, therefore give larger surplus of satisfaction to people. The larger this surplus, the more beneficial is the international trade.

6. Useful in cost-benefits analysis of projects: While undertaking any project the government
usually compare the cost of project and flow of benefits from project both in economic and in non-economic terms. E.g. For FLYOVER BRIDGE PROJECT the government will consider the consumers surplus Le. benefits in terms of time saving, fuel saving, etc. expected from flyover bridge project.

The CRITICISMS of the consumer’s surplus concept are as follows:-

  1. Imaginary: The concept of consumer’s surplus is quite imaginary idea. One has to imagine what you are prepared to pay and you proceed to deduct from that what you actually pay. It is all hypothetical and unreal.
  2. Cardinal measurement is not possible: Consumer’s surplus cannot be measured precisely because it is difficult to measure the total utilities and marginal utilities of the commodities consumed in quantitative terms.
  3. Ignores the interdependence between goods: The concept of consumer’s surplus does not consider the effect of availability and non-availability of substitutes and complementary goods on the consumption of a particular commodity. Actually consumer surplus derived from a commodity is affected by substitutes and complementary goods.
  4. Cannot be measured in terms of money: This is because the marginal utility of money changes as purchases are made and the consumer’s stock of money diminishes. But, Marshall assumed that-the marginal utility of money to be constant.
  5. Not applicable to Necessaries: It does not apply to the necessaries of life. In such cases the surplus is immeasurable e.g. – Food and Water. Consumer surplus is infinite because a consumer will stake whole of his income rather than go without them.
  6. Not applicable to prestige: e.g. – Diamonds jewellery, etc. fall in their prices lead to a fall in consumer’s surplus.

Indifference Curve Analysis

  • An indifference curve is a curve which represents combinations of two commodities that gives same level of satisfaction to the consumer.
  • As all the combinations give same level of satisfaction, the consumer becomes indifferent (Le. neutral) as to which combination he gets.
  • In other words, all the combinations lying on indifference curve are equally desirable and equally preferred by the consumer.

To Understand consider the following indifference schedule.

ca-foundation-business-economics-study-material-theory-of-consumer-behaviour-7

In the schedule I above, the consumer is indifferent whether he gets combination A, B, C or D. This is because all combinations give him same amount of satisfaction and therefore equally preferable to him. He gets as much satisfaction from 1 burger and 10 sandwiches as from 3 burgers and 3 sandwiches.

By plotting the above combinations on a graph, we can derive an indifference curve as shown in the following figure:

ca-foundation-business-economics-study-material-theory-of-consumer-behaviour-8

In the diagram, quantity of burger is measured on X-axis and quantity of sandwiches on Y-axis. The various combinations A, B, C, D are plotted and on joining them, we get a curve known as indifference curve. All combinations lying on the indifference curve give the same level of satisfaction to the consumer. Hence, the consumer is indifferent among them.

If the indifference schedule II is also plotted on the graph, we will get IC2. This will lie above the IC1 as all of IC2 combinations contain greater quantities of burgers and sandwiches. Similarly, we can draw IC3, IC4, etc… to make a complete indifference map as follows. Indifference map represents a full description of consumer’s tastes and preferences.

ca-foundation-business-economics-study-material-theory-of-consumer-behaviour-9

In the diagram, the various combinations E, F, G, H on IC2 give consumer same level of satisfaction and hence equally preferable to the consumer. The consumer is indifferent whether he gets combination E or F or any other combination.

The consumer however will prefer any combination lying on IC2 as it will give him more satisfaction than any combination lying on IC1.

This is because combinations lying on IC2 have larger quantity of burgers and sandwiches.

Thus, a higher indifference curve represents a higher level of satisfaction than lower indifference curve but HOW MUCH HIGHER cannot be indicated.

It is so because IC system is based on ORDINAL APPROACH according to which utility cannot be quantified but can only be compared.

Assumptions of indifference curve

  • Non-satiety: This assumption means that the consumer has not reached the point of full satisfaction in the consumption of any commodity. Therefore, a larger quantity of both commodities are preferred by the consumer. Larger the quantities of commodities, higher would be the total utility.
  • Rationality: Consumer is assumed to be rational. He aims at the maximisation of his total utility, given the market prices and money income. He is also assumed to have all relevant information like prices of goods, the markets where they are available, etc.
  • Consistency: The consumer is consistent in his choice Le. the preferences of consumers are consistent. If he prefers combination ‘A’ over combination ‘B’ in one period of time he will NOT prefer ‘B’ over ‘A’ in another period of time.
  • Transitivity: If combination A is preferred to B and ‘B’ is preferred to C, then, A is preferred to C. Symbolically, if A>B, and B>C, then A>C.
  • Ordinal Utility: It is assumed that consumer cannot measure precisely utility or satisfaction in absolute units Le. cardinally, but he can express utility ordinally. In other words, consumer is capable of comparing and ranking satisfaction derived from various goods and their combinations.
  • Diminishing Marginal Rate of Substitution: It means that as more and more units of ‘A’ are substituted for ‘B’ consumer will sacrifice lesser and lesser units of ‘B’ for each additional unit of ‘A’.

Marginal Rate of Substitution

  • The concept of marginal rate of substitution is the basis of Indifference Curves in the Theory of Consumer’s Behaviour.
  • IT MAY BE DEFINED AS THE RATE AT WHICH A CONSUMER WILL EXCHANGE SUCCESSIVE UNITS OF ONE GOOD (COMMODITY) FOR ANOTHER.

Consider the following schedule-

ca-foundation-business-economics-study-material-theory-of-consumer-behaviour-10

  • The above schedule shows the combinations of two goods ‘X’ and ‘Y’. Suppose the consumer wants more of ‘X’. To do so he must sacrifice some units of ‘Y’. in order to maintain same level of satisfaction.
  • Initially, the consumer sacrifices 4Y to get 1X, to obtain second unit of ‘X’ he sacrifices 2Y and so on.
  • This rate of sacrifice is technically called Marginal Rate of Substitution (MRS).
  • Thus, for any goods X and Y, the MRS is the loss of Y which can just be compensated by a gain of X. MRSxy goes on diminishing.

We can also measure MRS on an indifference curve. Consider the following diagram-

ca-foundation-business-economics-study-material-theory-of-consumer-behaviour-11

In the diagram, when the consumer moves from combination A to combination B, he gives up AC of Y and takes up CB of X and gets the same level of satisfaction.

ca-foundation-business-economics-study-material-theory-of-consumer-behaviour-12
MRSxy between two points is also the slope of the indifference curve between these two points. As the consumer moves from combination B to C, C to D, the MRSxy goes on diminishing.

The MRS goes on diminishing due to following reasons-

  1. The want for a particular commodity is satiable. So, as the consumer has more and more
    of that commodity, he is willing to take less and less of it. Thus, in the above example, when the consumer has more and more of ‘X’, his intensity of want for X’ diminishes but for ‘Y’ increases. Therefore, he does not want more of ‘X’ now and is not ready to H sacrifice more number of ‘Y’ for ‘X’.
  2. The second reason is that, the goods are not perfect substitutes of each other in the satisfaction of particular want. If they are perfect substitutes, the MRS would not fall and remain constant.

Properties of Indifference Curves

(Refer to Schedule I and above diagram)

Indifference curves always slope downwards from left to right:

  1. This means that an indifference curve has a negative slope.
  2. REASON – In order to maintain same level of satisfaction, as the quantity of burgers is increased in the combination, the quantity of sandwiches is reduced.
  3. Thus, this property follows from the definition of an IC and non-satiety assumption ie. more is preferred to less.
  4. Indifference curve cannot be horizontal straight line or vertical straight line or positively sloped.

Indifference Curves are convex to the origin:

  1. This means that IC is relatively steeper first in its left hand portion and tends to become relatively flatter in its right hand portion.
  2. REASON: Diminishing Marginal Rate of Substitution.
  3. The schedule and diagram shows that the consumer sacrifices less and less of sandwiches for every additional unit of burger.
  4. The convexity of an IC means that the two commodities can substitute each other but are not perfect substitute.
  5. If IC were concave to origin, it would mean increasing MRS. This is against the assumption of diminishing MRS.
    Similarly, IC cannot be straight lines as it would mean that MRS remains constant (for perfect substitute.)

Higher Indifference Curves Represents Higher Level of Satisfaction:

  1. In an indifference map, combinations lying on a higher IC gives higher level of satisfaction than the combinations lying on a lower IC. But how much higher cannot be indicated.
  2. REASON: This is because combinations on higher IC contains more quantity of either sandwiches or burger without having less of other as shown in the following diagram.
    ca-foundation-business-economics-study-material-theory-of-consumer-behaviour-13
  3. Combinations B and C on IC2 will be preferred by the consumer than the combination A on IC1.
  4. Combination B on IC2 contains more quantity of sandwiches without having less of burgers compared to combination A on IC1.
  5. Hence, all combinations on IC2 gives more satisfaction to consumer. Thus, higher IC represents higher satisfaction.

Indifference curves cannot intersect each other:

  1. It means that only one IC will pass through a point in the indifference map.
  2. In other words, ONE combination can lie only on one IC.
  3. Higher IC represents higher level of satisfaction and lower IC represents lower level of satisfaction. If they intersect each other, it would lead to illogical result.
  4. It can be proved with the help of following diagram –
    ca-foundation-business-economics-study-material-theory-of-consumer-behaviour-14

In the diagram two IC intersect each other at point A. On IC1; combinations A = B and on IC2, Combinations A = C. Therefore, by assumption of transitivity if, A = B and A = C. ∴ B = C. But C>B as it lie on higher IC giving higher satisfaction due to more quantity of sandwiches. So two IC cannot intersect.

Indifference curve will not touch either X-axis or Y-axis

ca-foundation-business-economics-study-material-theory-of-consumer-behaviour-15

  1. The indifference curve will not touch either X-axis or Y-axis because we have assumed that consumer is considering the different combinations of TWO commodities.
  2. If IC touches either of the axis, it would mean that consumer is interested in one commodity only.
  3. In the diagram IC touches X-axis at point B and Y-axis at point A.
  4. At point B the consumer is satisfied with OB quantity of X-commodity and zero quantity of A. This is against the definition of IC. Therefore, IC curve will not touch either axis.

Budget Line Or Price Line (Or Price Opportunity Line Or Expenditure Line Or Budget Constraint or Consumption Possibility Line)

  • A higher indifference curve shows a higher level of satisfaction than lower one.
  • Therefore, to maximize satisfaction consumer will try to reach the highest possible indifference curve.
  • He will try to buy more and more goods to get more and more satisfaction. But, what and how much a consumer can actually buy depends on –
    1. The money income of consumer,
    2. Prices of goods he wants to buy. They are the two objective factors which form the budgetary constraint of the consumer.

The budgetary position of the consumer can be graphically shown by BUDGET LINE. A budget line or price line shows maximum quantity of the different combinations of TWO GOODS that the consumer can purchase with his given money income and given market prices of goods.
Example:
The consumer’s money income is Rs. 100 to spend on X and Y.
Price of X is Rs. 5 per unit Price of Y is Rs. 2 per unit
Therefore, the consumer can get either 20 units of X and no Y.
OR
50 units of Y and no X.
OR
Combination of X and Y
Hence, 20 X and 50 Y form the two extreme limits of his expenditure. But the consumer can buy any ONE of the many combinations of X and Y within these limits. Graphically it can be shown as followsca-foundation-business-economics-study-material-theory-of-consumer-behaviour-16
This budget line corresponds to the following equation, called Budget Line Equation
Px. X + Py. Y = M
Where-
M = Total Money Income
Px = Price of commodity ‘X’
X = Quantity of X commodity
Py = Price of commodity
Y = Quantity of ‘Y’ commodity

It can be seen in the diagram that the consumer can buy a maximum of 20 units of X as denoted by points ‘L’ or buy a maximum of 50 units of Y as denoted by point ‘P’. On joining points P &L, we get a line PL called as budget line. It determines the limit or boundary of purchase.

The consumer can choose any combination of X and Y lying on budget line like combinations ‘a’ (8 X & 30 Y) or ‘b’ (12 X & 20 Y) or any other combination. However, the consumer cannot choose combination ‘Z’ as it is beyond his means i.e. budget. Any combination like ‘S’ lying within the budget line, shows under spending by consumer.

The slope of budget line is equal to the ratio of the prices of two goods Le. ratio of the prices of X to the price of Y. Thus, the slope of the budget line PL is Px/Py

Consumer’s equilibrium

  • The consumer is said to be in equilibrium when he maximizes his satisfaction (i.e. utility).
  • To explain the consumer’s equilibrium under ordinal approach, we have to make use of TWO TOOLS of indifference curve analysis namely-
    1. the consumer’s INDIFFERENCE MAP, and
    2. his PRICE/BUDGET LINE.

Assumptions:

  • The consumer has a fixed amount of money income to spend.
  • The consumer intends to buy TWO GOODS.
  • The Consumer is RATIONAL and tries to maximise his satisfaction.
  • The prices of two goods are GIVEN and are CONSTANT. Therefore, budget line has constant slope.
  • Goods are HOMOGENEOUS and DIVISIBLE.
  • The scale of preference of consumer Le. his taste & preferences remains unchanged. Scale of preference is expressed through indifference map.

The CONSUMER’S INDIFFERENCE MAP shows all indifference curves which rank the consumer’s preferences between various possible combinations of TWO commodities.

  • To maximises his satisfaction consumer would like to reach highest possible indifference curve.
  • The slope of IC at any one point shows the MARGINAL RATE OF SUBSTITUTION (which diminishes).
    ca-foundation-business-economics-study-material-theory-of-consumer-behaviour-17
  • To maximise satisfaction consumer will try to reach the highest possible IC and so will try to buy more and more of the two commodities.
  • But there are limits to which he can go on and on.
  • These limits are imposed (i) his money income, & (ii) prices of the commodities. These limits are described by PRICE/BUDGET LINE which shows the various combinations of two commodities the consumer can afford to buy.
  • All the combinations lying on the budget line are affordable by the consumer. Any, combination lying beyond budget line is unaffordable.
  • The slope of budget/price line shows the ratio of the prices of two commodities ie. Px/Py
  • Now we can show how a consumer reaches equilibrium ie., how he allocates his money expenditure between commodities X and Y and gets maximum satisfaction.

For showing this, we will have to superimpose the price line on the indifference map as follows-

ca-foundation-business-economics-study-material-theory-of-consumer-behaviour-18

  • In order to maximise his satisfaction, the consumer will try to reach highest IC ie. IC4.
  • But the budget constraint forces him to remain ON THE BUDGET LINE.
  • In the diagram, budget line PL shows all the combinations of X & Y that the consumer can buy. In diagram, we find combinations a, b, c, d, e lie on budget line PL and hence are affordable.
  • Points a,b,d and e lie on lower ICs and so are not the points of equilibrium as the consumer can get more satisfaction with the same amount of money.
  • Point ‘C’is the point of equilibrium as it lies on budget line and also on highest possible indifference curve IC3 giving maximum satisfaction.
  • At ‘point’ ‘C’, the budget line PL is TANGENT to indifference curve IC3.
  • At the point of tangency, Slope of indifference Curve = Slope of Budget Line
    ca-foundation-business-economics-study-material-theory-of-consumer-behaviour-19
  • Thus, the consumer is at equilibrium when
    ca-foundation-business-economics-study-material-theory-of-consumer-behaviour-20

 

RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions VSAQS

RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions VSAQS

These Solutions are part of RD Sharma Class 10 Solutions. Here we have given RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions VSAQS

Other Exercises

Answer each of the following questions either in one word or one sentence or as per requirement of the questions :
Question 1.
Define an arithmetic progression.
Solution:
A sequence a1, a2, a3, …, an is called an arithmetic progression of then exists a constant d
Such that a2 – a1 = d, a3 – a2 = d, ………… an – an-1 = d
and so on and d is called common difference

Question 2.
Write the common difference of an A.P. whose nth term is an = 3n + 7.
Solution:
an = 3n + 7
a1 = 3 x 1 + 7 = 3 + 7 = 10
a2 = 3 x 2 + 7 = 6 + 7 = 13
a3 = 3 x 3 + 7 = 9 + 7 = 16
d = a3 – a2 or a2 – a1 = 16 – 13 = 3 or 13 – 10 = 3

Question 3.
Which term of the sequence 114, 109, 104, … is the first negative term ?
Solution:
Sequence is 114, 109, 104, …..
Let an term be negative
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions VSAQS 1

Question 4.
Write the value of a30 – a10 for the A.P. 4, 9, 14, 19, …………
Solution:
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions VSAQS 2

Question 5.
Write 5th term from the end of the A.P. 3, 5, 7, 9,…, 201.
Solution:
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions VSAQS 3
= 3 + 190 = 193
5th term from the end = 193

Question 6.
Write the value of x for which 2x, x + 10 and 3x + 2 are in A.P.
Solution:
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions VSAQS 4

Question 7.
Write the nth term of an A.P. the sum of whose n terms is Sn.
Solution:
Sum of n terms = Sn
Let a be the first term and d be the common difference an =Sn – Sn-1

Question 8.
Write the sum of first n odd natural numbers.
Solution:
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions VSAQS 5

Question 9.
Write the sum of first n even natural numbers.
Solution:
First n even natural numbers are
2, 4, 6, 8, ……….
Here a = 2, d = 2
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions VSAQS 6

Question 10.
If the sum of n terms of an A.P. is Sn = 3n² + 5n. Write its common difference.
Solution:
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions VSAQS 7

Question 11.
Write the expression for the common difference of an A.P. Whose first term is a and nth term is b.
Solution:
First term of an A.P. = a
and an = a + (n – 1) d = b .
Subtracting, b – a = (n – 1) d
d = \(\frac { b – a }{ n – 1 }\)

Question 12.
The first term of an A.P. is p and its common difference is q. Find its 10th term. [CBSE 2008]
Solution:
First term of an A.P. (a) = p
and common difference (d) = q
a10 = a + (n – 1) d
= p + (10 – 1) q = p + 9q

Question 13.
For what value of p are 2p + 1, 13, 5p – 3 are three consecutive terms of an A.P.? [CBSE 2009]
Solution:
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions VSAQS 8

Question 14.
If \(\frac { 4 }{ 5 }\), a, 2 are three consecutive terms of an A.P., then find the value of a.
Solution:
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions VSAQS 9

Question 15.
If the sum of first p term of an A.P. is ap² + bp, find its common difference.
Solution:
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions VSAQS 10

Question 16.
Find the 9th term from the end of the A.P. 5, 9, 13, …, 185. [CBSE 2016]
Solution:
Here first term, a = 5
Common difference, d = 9 – 5 = 4
Last term, l = 185
nth term from the end = l – (n – 1) d
9th term from the end = 185 – (9 – 1) 4 = 185 – 8 x 4 = 185 – 32 = 153

Question 17.
For what value of k will the consecutive terms 2k + 1, 3k + 3 and 5k – 1 form on A.P.? [CBSE 2016]
Solution:
(3k + 3) – (2k + 1) = (5k – 1) – (3k + 3)
3k + 3 – 2k – 1 = 5k – 1 – 3k – 3
k + 2 = 2k – 4
2k – k = 2 + 4
k = 6

Question 18.
Write the nth term of the A.P.
\(\frac { 1 }{ m }\) , \(\frac { 1 + m }{ m }\) , \(\frac { 1 + 2m }{ m }\) , ……… [CBSE 2017]
Solution:
RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions VSAQS 11

Hope given RD Sharma Class 10 Solutions Chapter 5 Arithmetic Progressions VSAQS are helpful to complete your math homework.

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