Question

f a transversal intersects two parallel lines, then ____ angles are congruent.

Answer 1

Then alternate interior angles are always congruent. Can you imagine a Z with the top and bottom lines being the parallel ones and the angled line being the transversal?
If you find the midpoint of the transversal and rotate the Z a half turn (180 deg) around this midpoint then alternate interior angles map onto each other.
Under rotation angles are congruent. https://answers.yahoo.com/question/index?qid=20081212080631AA0wsKx

Answer 2

Also wrong section this belongs in math. :p