Parallelogram ABCD is shown with diagonal AC drawn. (Remember, opposite sides of a parallelogram are PARALLEL). Which proves that ∠DCA is ≌ to ∠BAC? (THINK about what kind of angles they are when two lines are parallel - DC is parallel to AB) If two parallel lines are cut by a transversal, then alternate exterior angles are congruent.
If two parallel lines are cut by a transversal, then corresponding angles are congruent.
If two parallel lines are cut by a transversal, then alternate interior angles are congruent.
If two parallel lines are cut by a transversal, the complementary angles are congruent.