Table of Contents

## Definition

2 Angles are Supplementary when they add up to 180 degrees.

Supplement comes from Latinsupplere, to complete or “supply” what is needed.

These two angles (120° and 60°) are Supplementary Angles, because they add up to 180° and make a straight angle.

But the angles don’t have to be together.

These 2 angles are supplementary because 120° + 60° = 180°

When the two angles add to 180°, we say they “Supplement” each other.

## Supplementary Vs Complementary

A related idea is Complementary Angles, they add up to 90°

How to remember which is which? Just think:

“S” of Supplementary | stands for “Straight” (a straight line) |

“C” of Complementary | stands for “Corner” (a Right Angle) |