Rylan wrote a proof to show that the measure of interior angles of a triangle add up to 180°. He also drew ∆ABC and line DE¯¯¯¯¯ that is parallel to AB¯¯¯¯¯ and passes through point C. Statements Reasons
1. AB is parallel to line DE. Given
2.(blank) Alternate interior angles are congruent
3.(blank) Angles that make up a line add to 180°
4.∠A+∠B+∠ACB=180° Substitution
Part A:
In the statement for step 2, ∠A is congruent to which angle? Which angle is ∠B congruent to?

Part B:
What is the missing statement in step 3?