# Proving Lines Are Parallel

Students learn the converse of the parallel line postulate and the converse of each of the theorems covered in the previous lesson, which are as follows. If two lines are cut by a transversal and corresponding angles are congruent, then the lines are parallel. If two lines are cut by a transversal and alternate interior angles are congruent, then the lines are parallel. If two lines are cut by a transversal and same-side interior angles are supplementary, then the lines are parallel. Students are then asked to determine which lines are parallel in given figures using information about the angles in the figures.