1. 2-3 Parallel lines and triangle angle sums
Homework:
16-27

2. In this Chapter I can…
2-1: determine angle measurements from parallel lines cut by a transversal
2-2: use angle relationships to prove that lines are parallel
2-3: use interior and exterior angles of triangles to solve problems
2-4: calculate the slope of parallel and perpendicular lines

3. Prove the angles in a triangle add to 180
Given: AB ll DC
Prove: <1+<2+<3=180°
Statement Reason 1) AB ll DC 1) Given 2)<3+<4+<5=180° 2) Supplementary Angles 3) <1≅<4 3) Alt. Interior Angles 4) <2≅<5 4) Alt. Interior Angles 5) <1+<2+<3=180° 5) Substitution D C 4 5 3 1 2 A B

4. example
x = 64
y = 74
z = 116 𝒛°
Triangle Exterior Sum
(Theorem)