1. Select Answers to Homework 2-3 9. Definition of Segment Bisector 10. 55 13. 914. 8 2-4 8. 90-2x, 180-2x11. RIV 21. 4423. 24, 72, 18

2. 2-6 Planning a Proof No Warm Ups!!!

3. Theorem If two angles are supplements of congruent angles (or the same angle), then the two angles are congruent If angles 1 and 2 are supplements and angles 3 and 4 are supplements and angle 1 and 3 are congruent then angles 2 and 4 are congruent

4. Theorem If two angles are complements of congruent angles (or the same angle), then the two angles are congruent If angles 1 and 2 are complements and angles 1 and 3 are complements then angles 2 and 3 are congruent

5. Proof of the Theorem Step 1. 1&2 are supp 3&4 are supp 2. 3. 4. Reason 1. Given 2. Def. of Supplements 3. Substitution Property 4. Subtraction Property

6. Planning a Proof Draw a diagram and mark it with given information Start with the given, end with the prove Think backwards (how can I prove this?) Look at the above steps, what do they tell you? Tell me why you think the “prove” is true Look at the picture, what else can you tell me?

7. Proof Step 1. 2. 3. 4. Reason 1. Given 2. Angle Addition Post. 3. Substitution Property 4. Subtraction Property 1234 1&2 are supp, 3&4 are supp Def. of Supplements If 2 angles are supp. of congruent angles, then they are congruent.

8. Homework Page 63 #1-17 19(3 steps) 20(5 steps) 21(4 steps) Flash Cards – Two new theorems (remember “If” on front, “Then” on back)