In problem 1-93, Althea showed that the shaded angles in the diagram are congruent. These angles are called alternate interior angles. They are called “alternate” because they are on opposite sides of the transversal, and “interior” because they are both inside (that is, between) the parallel lines. Is there another pair of alternate interior angles in this diagram? Which ones? Think about the relationship between the measures of alternate interior angles. If the lines are parallel, are they always congruent? Are they always supplementary? Complete the conjecture, “If lines crossed by a transversal are parallel, then alternate interior angles are…” Instead of writing conditional statements, Roxie likes to write arrow diagrams to express her conjectures. She expresses the conjecture from part (b) as: Lines are parallel alternate interior angles are congruent. This arrow diagram says the same thing as the conditional statement you wrote in part (b). How is it different from your conditional statement? What does the arrow mean? Prove that if parallel lines are crossed by a transversal, then the alternate interior angles are congruent. That is, use rigid transformations to map onto . Explain. Be sure your team agrees.