Angles are not the only type of figure that can be congruent. For example, the sides of a figure can be congruent to another side. Also, a complex shape (such as a trapezoid) can be congruent to another if there is a sequence of rigid transformations that carry it onto the other. Consider an isosceles triangle, like the one shown below. Because of its reflection symmetry, which parts must be congruent? State each relationship using symbols.

Triangle B A C with reflection symmetry. Side B, A, and side A C have equal length. There is a dashed line of reflection through vertex B perpendicular to side A,