Angle of Depression

Definition of Angle of Depression

The word "depression" means "fall" or "drop".

Angle of depression is the angle between the horizontal and the line of sight to an object beneath the horizontal.
Take a look at the example below.

Examples of Angle of Depression

In the picture below, an observer is standing at the top of a building and looking straight ahead at the birds (horizontal line). The observer must lower his eyes to see the car parked (slanting line).
The angle formed between the two lines is called the angle of depression.

exAngle of Depressionple of Angle of Depression

Video Examples: How to Solve Trig Application Problems: Angle of Depression

Solved Example Clockwise on Angle of Depression

Ques: An airplane is flying at a height of 2 miles above the level ground. The angle of depression from the plane to the foot of a tree is 15o. Find the distance that the air plane must fly to be directly above the tree.


  • Step 1: Let's first visualize the situation.
  • Step 2: Let 'x' be the distance the airplane must fly to be directly above the tree.
  • Step 3: The level ground and the horizontal are parallel, so the alternate interior angles are equal in measure.
  • img
  • img
  • Step 6: So, the airplane must fly about 7.46 miles to be directly above the tree.

Translate :

Please provide your email for a free trial as a Teacher or Student. This trial will be valid for the current academic year (2015-16). An email to this address includes the password to login to the full web application. You will also receive other promotional emails as and when such deals become available.

I am a Teacher Student