1. Complementary and Supplementary Angles

2. Complementary Angles
Two angles are complementary if the sum of their angles equals 90*.
If one angle is known, its complementary angle can be found by subtracting the measure of its angle from 90*.

3. Example of Complementary Angles
What is the complementary angle of 43*?
SOLUTION: 90* - 43* = 47*
So, 43* and 47* are complementary angles
Angle A measures 25* and Angle B measures 65*. Angle A and Angle B are complementary angles because together they create a 90* angle.
JUSTIFICATION: 25* + 65* = 90*

4. C C C C How can I remember that? Draw the C in Complementary
Since complementary angles equal 90*, turn that C into a number 9 by drawing a line, then add a 0 after that to make it 90.
So you change the C in complementary into 90*!!
C C C

5. Another way to remember…
Just remember this phrase:
“It is always RIGHT to give COMPLIMENTS”
A RIGHT angle is 90* and COMPLIMENT and COMPLEMENTARY sound alike

6. Click on the link below to manipulate different angles that are Supplementary.

7. Supplementary Angles
Two angles are supplementary if the sum of their angles equals 180*.
If one angle is known, its supplementary angle can be found by subtracting the measure of its angle from 180*.

8. Example of Supplementary Angles
What is the supplementary angle of 143*?
SOLUTION: 180* - 143* = 37*
Angle A measures 120* and Angle B measures 60*. Angle A and Angle B are complementary angles because together they create a 180* angle.
JUSTIFICATION: 120* + 60* = 180*

9. S S S 1S0* How can I remember that? Draw the S in Supplementary
Since supplementary angles equal 180*, turn that S into a number 8 by drawing a line diagonal, then add a 1 in front of that and a 0 after to make it 180.
So you change the S in supplementary into 180*!!
S S 1S0*

10. Click on the link below to manipulate different angles that are Supplementary.