MEDIUM
10th CBSE
IMPORTANT
Earn 100

Shown below is a rectangular tub of water of depth 34 cm. An object O is at the bottom of the tub. The image of the object is formed at I for an observer at Q.

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(Note: The figure is not to scale)

Find the distance by which the object seem to be moved for the observer. Show your work and give valid reasons.

(Note: Take 2=1.4, 3=1.7)

Important Questions on Some Applications of Trigonometry

EASY
10th CBSE
IMPORTANT

In the figure below, the height of the girl is 1.5 m and the height of the tree is 13.5 m.

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(Note: The figure is not to scale)

If AB=123 m, what is the angle of elevation (without symbol) of the top of the tree from her eyes? Show your steps.

HARD
10th CBSE
IMPORTANT

In the giant wheel shown below, Gagan is sitting in one of the cabins which is 12 m high from the platform. Jyoti and Karan are sitting in the lowest and the highest cabins from the platform respectively.

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(Note: The figure is not to scale)

From Gagan, the angle of depression of Jothi and the angle of elevation of Kiran is 30° and 60° respectively.

i) What will be the angle of elevation of Gagan from Jyoti?

ii) What will be the angle of depression of Gagan from Kiran?

iii) Find the diameter of the giant wheel.

Show your steps with a diagram.

MEDIUM
10th CBSE
IMPORTANT

A ship was moving towards the shore at a uniform speed of 36 km/h. Initially, the ship was 1.3 km away from the foot of a lighthouse which is 173.2 m in height.

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(Note: The figure is not to scale)

Find the angle of depression, x, (without symbol) of the top of the lighthouse from the ship after the ship had been moving for 2 minutes.

Show your steps and give reasons. (Take 3 as 1.732 and 2 as 1.414)

MEDIUM
10th CBSE
IMPORTANT

Shown below is a submarine scouting an enemy ship in the ocean using a sonar device. Sonar devices send out a sound pulse from a transducer, and then precisely measure the time it takes for the sound pulses to be reflected back to the transducer.

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A sonar wave sent by the submarine hits the ship and returns back in 2 seconds. The speed of a sonar wave underwater is 1500 m/s and the submarine is diving at a depth of 750 m below sea level.

Find the angle of elevation 'a' (without units) of the ship from the submarine (without symbol). Show your steps.

MEDIUM
10th CBSE
IMPORTANT

The position of an eagle and two identical geese are shown in the figure below. All the birds are at the same height from the ground. Assume that the eagle can fly at the same speed in all directions and that the geese are unaware of the Eagle's intention and will not move from their positions.

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(Note: The figure is not to scale)

If the eagle wants to attack the goose that is nearer to it, which one should it attack? Show your steps.

HARD
10th CBSE
IMPORTANT

Two trees are 2d meters apart. Ajay stood at a point midway between them and started walking in a direction perpendicular to the line connecting the two trees. After walking d metres, he observed the angle of elevations to the tops of the two trees and found them to be complementary.

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(Note: The figure is not to scale)

If one of the trees is thrice as tall as the other, find the height of the shorter tree, in terms of d. Show your work.

HARD
10th CBSE
IMPORTANT

If the angle of elevation of a cloud from a point h metres above a lake is α and the angle of depression of its reflection in the lake is β, prove that the height of the cloud is :

h tan β+tan αtan β-tan α

HARD
10th CBSE
IMPORTANT
From a point P on the ground, the angle of elevation of the top of a 10 m tall building is 30°. A flag is hoisted at the top of the building and the angle of elevation of the top of the flagstaff from P is 45°. Find the length of the flagstaff and the distance of the building from the point P. (Take 3=1.732).