∫△ABC and△△△ AED are right triangles.
∴∠ BAC = ∠ EAD = 90 (4 points)
∴∠BAC+∠CAE=∠EAD+∠CAE means ∠BAE=∠CAD(6 points).
AB = AC，AE=AD，
∴△ Abbe△ ?△ACD(SAS). (10)