# Important Questions for CBSE Class 10 Maths Chapter 9 - Some Applications of Trigonometry 3 Mark Question

## CBSE Class 10 Maths Chapter-9 Some Applications of Trigonometry – Free PDF Download

Free PDF download of Important Questions with Answers for CBSE Class 10 Maths Chapter 9 – Some Applications of Trigonometry prepared by expert Maths teachers from latest edition of CBSE(NCERT) books only by CoolGyan to score more marks in CBSE board examination.

CBSE Class 10 Maths Chapter-9 Some Applications of Trigonometry Important Questions

## 3 Mark Questions

1. A 1.5 m tall boy is standing at some distance from a 30 m tall building. The angle of elevation from his eyes to the top of the building increases from  to  as he walks towards the building. Find the distance he walked towards the building.

Ans. AB = 30 m and PR = 1.5 m
AC = AB – BC
= AB – PR
= 30 – 1.5
= 28.5 m
In right triangle ACQ,

QC =  m
In right triangle ACP,

PQ =
PQ =  =  m
Hence, the walked towards the building is  m.

2. From a point on the ground, the angles of elevation of the bottom and the top of a transmission tower fixed at the top of a 20 m high building are  and  respectively. Find the height of the tower.

Ans. Let the height of the tower be  m. Then,
in right triangle CBP,

……….(i)
In right triangle ABP,

BP = 20 m
Putting this value in eq. (i), we get,
=

m
The height of the tower is  m.

3. A statue, 1.6 m tall, stands on the top of a postal. From a point on the ground, the angle of elevation of the top of the statue is  and from the same point the angle of elevation of the top of the pedestal is  Find the height of the pedestal.

Ans. Let the height of the pedestal be  m.
BC =  m
In right triangle ACP,

……….(i)
In right triangle BCP,

PC =
[From eq. (i)]

m

4. As observed from the top of a 75 m high lighthouse from the sea-level, the angles of depression of two ships are  and  If one ship is exactly behind the other on the same side of the lighthouse, find the distance between two ships.

Ans. In right triangle ABQ,

BQ = 75 m ……….(i)
In right triangle ABP,

[From eq. (i)]
75 + QP =
QP =  m
Hence the distance between the two ships is  m.

5. A girl who is 1.2 m tall, spots a balloon moving with the wind in a horizontal line at a height of 88.2 m from the ground. The angle of elevation of the balloon from the eye of the girl at any instant is . After sometime, the angle of elevation reduces to . Find the distance travelled by the balloon during the interval.

Ans.
In right

In right

6. From the top of a tower 96 m high, the angles of depression of two cars on a road at the same level as the base of the tower and on same side of it are θ and , where and . Find the distance between the two cars.

Ans.
In right

In right