1. Warm up 1.Write the converse, inverse, contrapositive of: If it’s Mr. Harms, then he has back hair. 2. Are you able to write a biconditional? Why or why not? 3. Find x 3x -5 = x + 10 4. Find x x 2 + 3x + 2 = 0

2. 2.5 Conjectures & Theorems ♥A conjecture is a GUESS ♥A theorem has been PROVEN to be true – there are no counterexamples.

3. Vertical Angles Vertical angles are formed by the intersection of 2 lines or segments. Can you make a conjecture about the relationship of angles 1 & 2? How about angles 3 & 4? 1 2 34

4. Vertical Angles Theorem If two angles form a pair of vertical angles, then they are congruent. m<1 = m<4 m<2 = m<3 1 4 2 3

5. Reflections Across Parallel Lines Look at the first tree and the third tree: Reflection across two parallel lines is equivalent to a translation of twice the distance between the lines, in a direction perpendicular to the lines.

6. Review How many degrees are there in a line? How many degrees in a linear pair? 1 2 What is the name of this property? a = b b = c a = c Find the measures of all the missing angles: 72° 1 2 3 Find pairs of congruent angles A C B D E Z 180° transitive 72° 108° <A and <Z <C and <E <D and <B

7. Assignment 2 practice proofs worksheet Pg 121, 10-20, 44-50