2. Lesson 2-5 Postulates & Proofs

3. Proofs Defined: A way of organizing your thoughts and justifying your reasoning. Proofs use definitions and logic!

4. Example Proof Given: You do all your homework Prove: You will earn a homework pass StatementsReason 1) You do all your homework 1) Given 2) 100% homework average 2) Result of doing ALL your work 3) You earn a homework pass3) Defined class reward

5. What can you conclude if GIVEN: Isosceles Triangle: Equilateral Triangle: Perpendicular Lines: Parallel Lines: Midpoint: Complementary Angles: Supplementary Angles:

6. Example Proof E FG Given:  F is a right angle Prove:  E &  G are complementary StatementsReason 1)  F is a right angle 1) Given 2)  F = 90 2) Def. Of Right Angles 3)  F +  E +  G = 1803) Sum of Angles of  4) 90 +  E +  G = 180 4) Substitution 5)  E +  G = 90 5) Subtraction 6)  E &  G are complementary 6) Definition