NCERT Class 10 Chapter 9 Some Applications of Trigonometry Official CBSE Board Sample Problems Very Short Answer

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Question

An observer, 1 .7 m tall, is m away from a tower. The angle of elevation from the eye of observer to the top of tower is . Find the height of tower.

Solution

The angle of elevation

The Angle of Elevation

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Let CD be the tower of height h.

In ,

So, height of tower is 21.7 m. 4- 2O m

Question

A ladder, leaning against a wall, makes an angle of with the horizontal. If the foot of the ladder is 2.5 m away from the wall, find the length of the ladder.

Solution

Horizontal

Horizontal

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Let AC be the ladder of length x.

In

Thus, length of the ladder is 5 m.

Question

Horizontal and reaches

Horizontal and Reaches

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If Figure, AB is a 6 m high pole and CD is a ladder inclined at an angle of 600 to the horizontal and reaches up to a point D of pole. If, find the length of the ladder.(use )

Solution

Hence, Length of the ladder is 4 m.

Question

Find the value of AB if in triangle ABC right angled at B,

Solution

In triangle ABC,

Question

Tringle

Tringle

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In fig. a tower AB is 20 m high and BC, its shadow in the ground is m long. Find the sun’s altitude.

Solution

Let x be the required angle

In triangle ABC,

Question

An observer, 1.7 m tall is m away from a tower. The angle of elevation from the eye of the observer to the top of the tower is 30. Find the height of the tower.

Solution

The angle of elevation

The Angle of Elevation

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Let CD is the height of the tower be h

Question

A ladder, leaning against a wall makes an angle of 60 with the horizontal. If the foot of the ladder is 2.5 m away from the wall. Fund the length of the ladder.

Solution

Let AC ¡s the length of the ladder be x

The Horizantal

The Horizantal

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Question

From the top of a light house angles of depression of ship A and ship B are found to be and respectively. Which ship is closer to the light house?

Solution

Ship B

Question

As a plane moves away from a viewer what happens to the elevation of the plane as observed from the same observation point? Increases or decreases?

Solution

Decreases

Question

From the foot of a building the elevation of the top of a tower is and from the foot of the tower the elevation of the top of the building is . Which of the two is shorter?

Solution

Tower

Question

The angle of elevation of the top of a tower from the top of a rock is which is taller the rock or the tower?

Solution

Tower

Question

The shadow of a tower at a particular time of the day is equal to its height, what is the elevation of the source of light?

Solution

Question

The shadow of a tower at a particular time of the day is equal to its height, what is the elevation of the source of light?

Solution

Depression

Question

When a viewer looks at an object which is above his horizontal line of sight, his eyes turn through an angle, the angle through which his eyes turn is the angle of (fill in the blank)

Solution

Elevation

Question

An observer is 30 m away from a tower. The angle of elevation of the top of the tower from his eyes is °. Find the height of the tower.

Solution

Question

The length of the shadow of a tower is equal to its height. What is the altitude of the sun?

Solution

Let the height of the tower be h and so the shadow is also h. let the altitude of the sun be

So the altitude of the sun is 45 degrees