# Supplementary Angles

- Author:
- Judith Hilinski

- Topic:
- Angles

**Supplementary Angles are any pair of angles whose sum (adding) is equal to 180 degrees (straight angle).**

## Explicit Instruction: Supplementary Angles

**Remember that pairs are things that come in twos. For example, the pair of dice above is called a pair because there are two of them. Can you think of any other types of pairs?**

## Supplemental Angles

**So, any PAIR of angles that have a sum of 180 degrees are supplementary angles.**

**We can use that truth to solve problems in Geometry!**

## Supplemental Angle Problem

**We know that line m is a straight line.**

**If line m is a straight line, then we know its measure is 180 degrees We know that the larger angle has a measure of 118 degrees, but we don't know what the measure of its supplemental angle is (x**

**).**

**I set up an equation based on the postulate:**

**x + 118 = 180**

**I subtract 118 from both sides of the equal sign x = 62**