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