Two angles that add to 180° are are said to supplement each other.
A Real Example of Supplementary Angles
Angles of 100° and 80° are supplementary angles.
100° + 80° = 180°
How to Find a Supplementary Angle
What is the missing angle θ below?
The 56° angle and θ are supplementary angles. They add up to 180°.
56° + θ = 180°
Subtract the 56° angle from 180°.
θ = 180° − 56° = 124°
The missing angle θ is 124°.
The slider below shows another real example of supplementary angles.Open the slider in a new tab