The HL (hypotenuse leg) theorem states that any two right triangles that have a congruent hypotenuse and a corresponding, congruent leg are congruent triangles.
Explanation:
AE is congruent to itself.
AB is congruent to DE
<ADE and <EBA are right angles, making them right triangles
Therefore ADE is congruent to EBA by the HL theorem.