1. Complementary and Supplementary Angles

2. Angle 1
Angle 2
Angle 1 + Angle 2
Complementary Angles ?

3. Two angles are complementary if the sum of their angles equals 90⁰ forming a right angle.
If one angle is known, its complementary angle can be found by subtracting the measure of its angle from 90⁰.
Complementary Angles

4. Examples of Complementary Angles
What is the complementary angle of 43⁰?
SOLUTION: 90⁰ - 43⁰ = 47⁰
So, 43⁰ and 47⁰ are complementary angles
Angle A measures 25⁰ and Angle B measures 65⁰. Angle A and Angle B are complementary angles because together they create a 90⁰ angle.
JUSTIFICATION: 25⁰ + 65⁰ = 90⁰
Examples of Complementary Angles

5. How can I remember complementary?
Draw the C in Complementary C
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

6. Another way to remember…
Just remember this phrase:
“It is always RIGHT to give COMPLIMENTS”
A RIGHT angle is 90 ⁰ and COMPLIMENT and COMPLEMENTARY sound alike

7. Complementary Angles

8. Click on the link below to manipulate different angles that are Complementary.

9. Angle 1
Angle 2
Angle 1 + Angle 2
Supplementary Angles ?

10. Two angles are supplementary if the sum of their angles equals 180⁰.
If one angle is known, its supplementary angle can be found by subtracting the measure of its angle from 180⁰.
Supplementary Angles

11. Example of Supplementary Angles
What is the supplementary angle of 143⁰?
SOLUTION: 180⁰ - 143⁰ = 37⁰
Angle A measures 120⁰ and Angle B measures 60⁰. Angle A and Angle B are complementary angles because together they create a 180⁰ angle.
JUSTIFICATION: 120⁰ + 60⁰ = 180⁰
Example of Supplementary Angles

12. How can I remember supplementary?
Draw the S in Supplementary S
Since supplementary angles equal 180⁰, 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

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

14. Wrap it up . . . Complementary Angles add up to be 90⁰
Complementary Angles look like a right angle.
Supplementary Angles add up to be 180⁰
Supplementary Angles look like a straight line.
Wrap it up . . .