Answer
1. DE bisects CDA, so it follows that angle 2 and angle three are congruent.
2. Since angle one equals angle three, this means that angle one equals angle two.
3. Angle one and angle two are alternate interior angles cut by the transversal DA.
4. If alternate interior angles are congruent, the lines are parallel.
5. Angle one and two are congruent.
6. Line ED is parallel to AB.
