Angles of Elevation and Depression - JSS2 Mathematics Lesson Note

Angle of Elevation

The angle of elevation is the angle between the horizontal line and the line of sight looking up at an object.

Example

Imagine you're looking up at the top of a tall building from the ground. If you measure the angle from your line of sight (parallel to the ground) up to the top of the building, that is the angle of elevation.

Calculation

If you know the height of the building and the distance from the building, you can use trigonometry to find the angle of elevation.

tan(𝜃)

=height of the building/distance from the building

Source:(Cuemath.com)
 

Angle of Depression

The angle of depression is the angle between the horizontal line and the line of sight looking down at an object.

Source:(Cuemath.com)

Example

Imagine you are at the top of a lighthouse looking down at a boat in the sea. The angle formed between your line of sight (parallel to the ground) and the line from your eyes to the boat is the angle of depression.

Calculation

Similarly, if you know the height from which you are looking down and the horizontal distance to the object, you can calculate the angle of depression.

tan(𝜃)

=height from the object/distance to the object