1. Do Now

2. What do you call a 90° angle?
A right angle!
Definition: An angle is a right angle iff it is 90°.

3. Theorem: If two angles are right angles, then they are congruent
Remember: We have to *prove* theorems!

4. What do you call two angles that add up to 90°?B A B C
Definition: Two angles that add up to 90° are COMPLEMENTARY!

5. Theorems about Complementary Angles:
Theorem: If two angles are complements of the same angle, then they are congruent.
Let’s Prove It!!!!!!!!!!!!!!!!

6. If two angles are congruent, their complements are congruent.
Theorem:
If two angles are congruent, their complements are congruent.
Oh em gee pruv it.

7. Homework Prove theorem 5 and 6 on pg. 144.
Make a list of the theorems/postulates/definitions separate from your notes. I will be checking this every week. THIS WILL HELP YOU WHEN YOU DO PROOFS!