If two sides and the included angle of one triangle are equal to the corresponding sides and angle of another triangle, the triangles are congruent.
In ΔAEB and ΔDEC,
∠BEA≅∠CED ....vertically opposite angles
side EA≅ side EC ...radii of same circle
side EB≅ side ED ...radii of same circle
∴ΔAEB≅ΔDEC ....S.A.S test