## Elementary Geometry for College Students (6th Edition)

By ASA, $\triangle CAB \cong \triangle DAB$
Angle: $\angle CAB \cong \angle DAB$ Side: Both triangles share the side $\overline{AB}$, which is between two angles which are congruent. Angle: $\angle ABC \cong \angle ABD$ Therefore, by ASA, $\triangle CAB \cong \triangle DAB$