Exercise 73 Page 611

Let's add the given information about the sides. We also see that both triangles share $\overline{AB}$ as a side. Therefore, we know by the Reflexive Property of Congruence that this side is congruent.

Notice that $△AEB$ has two sides of equal length, which means it is an isosceles triangle. Using the Base Angles Theorem, we know that its base angles are congruent.

Now we have enough information to claim congruence between $△DAB$ and $△CBA$ using the Angle-Side-Angle (ASA) Congruence Theorem.