Using reflexive property (for side), and the transversals of the parallel lines, we can prove the two triangles are congruent.
Step-by-step explanation:
Since AB and DC are parallel and AC is intersecting in the middle, you can make out two pairs of alternate interior angles<em>.</em>These angle pairs are congruent because of the alternate interior angles theorem. The two pairs of congruent angles are: ∠DAC ≅ ∠BCA, and ∠BAC ≅ ∠DCA.
With the reflexive property, we know side AC ≅ AC.
Using Angle-Side-Angle theorem, we can prove ΔABC ≅ ΔCDA.
