# Angle of Elevation and Depression

In this revision note, you will learn to extend your knowledge of Trigonometry to find angle of elevation and depression.

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## Angle of Elevation

When you look at an object above your location, the angle formed between the horizontal ground and the line of sight is called the **angle of elevation**.

## Angle of Depression

When you look at an object below your location, the angle formed between the imaginary horizontal ground and the line of sight is called the **angle of depression.**

## Important Tips to Find Angle of Elevation and Depression

Always measure the angles from the horizontal line.

Angle of elevation is always **equal** value as angle of depression. They are **alternate angles.**

## Steps to Find Angle of Elevation and Depression

Step 1: Draw a sketch of the situation.

Step 2: Mark in the given angle of elevation or depression.

Step 3: Use trigonometry to find the required missing angle or length.

## Example 1 Angle of elevation

A boy flying a drone tracking its direction. The drone is 400 m away from the boy and the drone is flying at a vertical height of 250 m above the eye level. What is the angle of

elevation of the drone from the boy, measure from his eye level ?

Solution:

sin *θ* = 250/400

Angle of elevation,* θ = *38.7°

## Example 2 Angle of Depression

TY is a building of height 90 m. The angle of depression of a car C from the top T is 40°.

Find

(a) the value of ∠CTY.

(b) the value of ∠TCY.

(c) the distance between C and Y.

Solution:

(a)* ∠CTY* = 90° – 40° = 50°

(b)* ∠TCY = *40° (alt. ∠s)

(c)

tan 40° = 90/CY

CY = 90/ tan 40°

= 107.2578 (4 dp)

=107 m (3 sf)

## Last Minute Revision for O Level Math?

## Check out our exam guide on other topics here!

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