1. Welcome to class. ♥ Please get your folders. ♥ I need a couple of volunteers to hand out papers from the black tray. ♥ We are going to go over your last quiz and grade homework before we take today’s quiz. ♥ Eventually you will need a scissors and a glue stick

2. 2.5 Reasoning in Algebra and Geometry ♥ We accept postulates as true. ♥ We also accept the properties of equality from algebra as true.

3. ♥ We know the distributive property is true: ♥ And these properties of congruence:

4. Justifying Steps When Solving an Equation What is the value of x? Justify each step. 1.<AOM and <MOC are supplementary 2.m<AOM + m<MOC = 180 3.(2x + 30) + x = 180 4.3x +30 = 180 5.3x = 150 6.X = 50 (2x + 30) ◦ x◦x◦ AOC M 1.Angles that form a linear pair are supplementary 2.Definition of supplementary <s 3.Substitution Property 4.Distributive Property 5.Subtraction Property of Equality 6.Division Property of Equality

5. PROOF This will be your new best friend. Spend a lot of time with it ♥ ♥ A proof is a convincing argument that uses deductive reasoning. ♥ A proof logically shows why a conjecture is true. ♥ A two-column proof lists each statement on the left and the justification, or reason, on the right. ♥ Each statement must follow logically from the steps before it.

6. Two-Column Proof

9. Your assignment Pg 117; 5 – 41 all