The definition states that complementary angles are any two angles whose sum is 90°. (The angles do not have to be next to each other to be complementary.) As seen in the diagram on the left, a 30° angle

**+**a 60° angle = 90° so they are complementary angles. Notice that the two angles form a right angle or 1/4 of a circle.

If I write the word

**and change the first letter "C" into the number nine and I think of the letter "O" as the number zero, I have a memory trick my mathematical brain can remember.**

*complementary*
Supplementary Angles are two
angles whose sum is 180°. Again, the two angles do
not have to be together to be supplementary, just so long as the total is 180 degrees. In the illustration on your right, a 110° angle

**+**a 70° angle = 180°; so, they are supplementary angles. Together, they form a straight angle or 1/2 of a circle.
If I write the word

**and alter the "S" so it looks like an 8, I can mentally imagine 180°.***supplementary*
Since there are so many puns for geometric terms. I must close with a bit of geometry humor.

Having Fun With Angles |

Want a variety of hands-on ideas on how to introduce angles to your students?

Check out this resource.

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