Answer
1. It is given that AB is congruent to CD.
2. It is given that angle BAD is congruent to angle CDA.
3. By the identity theorem, it follows that AD is congruent to itself.
4. Thus, by SAS, triangle CAD is congruent to triangle BAD.
5. Thus, by the definition of congruent triangles, angle 1 and angle 2 are congruent.
6. Sides opposite congruent angles are congruent, so AE is congruent to ED.
