# RS Aggarwal Solutions Class 10 Height And Distance

## RS Aggarwal Solutions Class 10 Chapter 14

All these RS Aggarwal class 10 solutions Chapter 14 Height and Distance are solved by Byju's top ranked professors as per CBSE guidelines.

Q.1: ??A tower stands vertically on the ground. From a point on the ground which is 20m away from the foot of the tower, the angle of elevation of its top is found to be $$60^{\circ}$$. Find the height of the tower. [Take $$\sqrt{3}=1.732$$]

Sol:

Let AB be the tower standing on a level ground and 0 be the position of the observer. Then OA = 20 m and ???OAB = 90?? and ???AOB = 60??

Let AB = h meters

From the right ???OAB, we have

$$\frac{AB}{OA}$$ = Tan 60o = ???3

$$\frac{h}{20}$$ = ???3

h = (20 x ???3)

h = 20 x 1.732

h = 34.64m

Hence the height of the tower is 20???3 m = 34.64m

Q.2: A kite is flying at a height of 75m from the level ground, attached to a string inclined at $$60^{\circ}$$ to the horizontal. Find the length of the string, assuming that there is no slack in it. [Take $$\sqrt{3}=1.732$$]

Sol:

Let OB be the length of the string from the level of ground and 0 be the point of the observer, then,

AB = 75m and ???OAB = 90?? and ???AOB = 60??, let OB = I meters.

From the right ???OAB:

$$\frac{OB}{AB}$$ = cosec 60?? = $$\frac{2}{???3}$$

$$\frac{I}{75}$$ = $$\frac{2}{???3}$$

I = ( 75 x $$\frac{2}{???3}$$ x $$\frac{???3}{???3}$$ )

I = 25 x 2 x ???3

I = 50???3

I = 86.6m

Hence, the length of the string 86.6m

Q.3: The angle of depression from the top of a tower of a point A on the ground is $$30^{\circ}$$. On moving a distance of 20 meters from the point A towards the foot of the tower to a point B, the angle of elevation of the top of the tower from the point B is $$60^{\circ}$$. Find the height of the tower and its distance from the point A.

Sol:

Let CD be the tower and BD be the ground

Then, ???CBD = 30??, ???CAD = 60??

???BDC = 90??, AB = 20 m, CD = h metre and AD = x metre.

From ???BCD:

$$\frac{CD}{BD}$$ = tan 30??

= $$\frac{CD}{BD}$$

$$\frac{h}{20 + x}$$ = $$\frac{1}{???3}$$ = ???3h = 20 + x

???3h = 20 + x

=> x = ???3h ??? 20. ??????????????????????(1)

$$\frac{CD}{AD}$$ = tan 60??

$$\frac{h}{x}$$ = ???3

$$\frac{h}{???3}$$ = x ???????????.(2)

From (1) and (2) we get,

???3h ??? 20 = $$\frac{h}{???3}$$

=> 3h – 20???3 = h

=> h = 10???3 = 10×1.732 => 17.32

H = 17.32m and ????BD = 30m

Hence, the height of the tower = 17.32m and the distance of the tower from the point A = 30m.

Q.4: A vertical tower stands on a horizontal plane and is surmounted by a vertical flagstaff of height 5 m. At a point on the plane, the angle of elevation of the bottom of the flagstaff is $$30^{\circ}$$ and that of the top of the flagstaff is $$60^{\circ}$$. Find the height of the tower. [Use $$\sqrt{3}= 1.73$$]

Sol:

Let AB be the tower h meter high. CA is the flag staff 5 meter high.

Let PB = x meter

In ?????PBC,

???CPB = 60??, ???PBC = 90??

$$\frac{BC}{PB}$$ = tan 60??

$$\frac{5+x}{x}$$ = ???3

5 + h = ???3x ???????????.(1)

???APB = 30?? and ???ABP = 90??

$$\frac{AB}{PB}$$ = tan 30??

$$\frac{h}{x}$$ = $$\frac{1}{???3}$$

???3h = x

Putting value of x in (1), we get

5 + h = ???3 x ???3h => 3h

2h = 5

Or h = 5/2m

Thus, height of tower = 2.5m

Q.5: A statue 1.46m tall stands on the top of a pedestal. From a point on the ground, the angle of elevation of the top of the statue is $$60^{\circ}$$ and from the same point, the angle of elevation of the top of the pedestal is $$45^{\circ}$$. Find the height of the pedestal. [Use $$\sqrt{3}= 1.73$$]

Sol:

Let SP be the statue and PB be the pedestal. Angles of elevation of S and P are 60?? and 45?? respectively.

Further suppose AB = x m, PB = h m

In right ?????ABS,

$$\frac{SB}{AB}$$ = tan 60?? = ???3

$$\frac{h+1.46}{x}$$ = ???3 ????????(1)

In right ???????PAB,

$$\frac{PB}{AB}$$ = tan 45?? = 1

h = x ?????????.(2)

putting x = h in (1)

$$\frac{h + 1.46}{h}$$ = ???3

=> h + 1.46 = ???3 h

h = 0.73 x 2.732 = 2m (nearly)

Thus, the height of the pedestal = 2m.

Q.6: The angle of elevation of the top of a tower from a point on the same level as the foot of the tower is $$30^{\circ}$$. On advancing 150m towards the foot of the tower, the angle of elevation becomes $$60^{\circ}$$. Show that the height of the tower is 129.9 metres. [Given $$\sqrt{3}=1.732$$]

Sol:

Let AB be the tower and let the angle of elevation of its top at C be 30??. Let D be a point at a distance 150m from C such that the angle of elevation of the top of the tower at D is 60??. Let h m be the height of the tower and AD = x m.

In ?????CAB, we have

Tan 30?? = $$\frac{AB}{AC}$$

=> $$\frac{1}{???3}$$ = $$\frac{h}{x+150}$$ ???????????.(1)

In ??? DAB, we have

Tan 60?? = $$\frac{AB}{AD}$$ => ???3 = $$\frac{h}{x}$$

X = $$\frac{h}{???3}$$ ????????(2)

Putting the x = $$\frac{h}{???3}$$ ????in (1), we get

=> $$\frac{1}{???3}$$ ??= $$\frac{???3h}{h+150???3}$$

=> h+150???3 ??= ??3h ??=> 3h ??? h = 150???3

2h = 150???3

h = 75???3

h = (75×1.732)m

h = 129.9

Hence the height of tower is 129.9 m

Q.7: On a horizontal plane there is a vertical tower with a flagpole on the top of the tower. At a point, 9 meters away from the foot of the tower, the angle of elevation of the top and bottom of the flagpole are $$60^{\circ}\:and\:30^{\circ}$$ respectively. Find the height of the tower and the flagpole mounted on it. [Take $$\sqrt{3}=1.73$$]

Sol:

Let AB be the tower and BC be the flagpole, Let O be the point of observation. Then, OA = 9 m, ???AOB = 30?? and ???AOC = 60??

From right angled ???BOA:

$$\frac{AB}{OA}$$ ????= tan 30??

$$\frac{AB}{9}$$ = $$\frac{1}{???3}$$ ????=> AB = 3???3

From right angled ???OAC

$$\frac{AC}{OA}$$ ????= tan 60??

BC = (AC ??? AB) => 6???3m.

Thus, AB = 3???3m => 5.196m

BC = 6???3m => 10.392m

Hence, height of the tower= 5.196 m and,
height of the flagpole = 10.392 m