Corresponding angles of δabc and δdef are congruent. does this prove that the triangles are congruent? justify. a) yes; aaa guarantees that all corresponding parts of the two triangles are congruent. b) yes; aaa guarantees similarity and congruency because the triangles must have equal sides to have equal angles. c) no; aaa only guarantees similarity because the lengths of the sides of the two triangles are not necessarily equal. d) yes; aaa guarantees congruency because if at least two angles of a triangle are congruent to each other, then the triangles are congruent.