AC is common to the 2 triangles in question
angle BAC = angle DCA alternate interior angles of parallel lines are equal
angle ACB = angle CAD alternate interior angles of parallel lines are equal
triangle ACB is congruent to triangle CAD ASA
QED
P.S. Please tell me how you uploaded the figure to Wyzant! Thanks.
Juan C.
Thanks for the answer! I copied and pasted the figure in. It doesn't always work though. I wish there was an easy reliable way to upload figures.11/17/18