Complementary Angles

Complementary Angles

Complementary angles are two angles which add up to a right angle (90°).

Two angles that add to 90° are are said to complement each other.

A Real Example of Complementary Angles

Angles of 30° and 60° are complementary angles.

30° + 60° = 90°

How to Find a Complementary Angle


What is the missing angle θ below?



The 53° angle and θ are complementary angles. They add up to 90°.

53° + θ = 90°


Subtract the 53° angle from 90°.

θ = 90° − 53° = 37°


The missing angle θ is 37°.


The slider below shows another real example of complementary angles.

Open the slider in a new tab

See Also

What is an angle? What is a right angle? What is a right triangle? What is an acute angle?