What is one method used to determine if triangles are congruent?

Determining if triangles are congruent involves various criteria, and one of the primary methods is to assess the lengths of their sides. When two triangles have one pair of opposite sides that are equal in length, it is a strong indicator that the triangles could be congruent. However, to fully establish congruence, it is necessary to compare all sides or angles as per congruence criteria such as Side-Side-Side (SSS) or Side-Angle-Side (SAS).

While equal angles or the sum of angles can indicate similarities between triangles, they do not guarantee congruence on their own without considering side lengths. The parallelism of sides does not contribute to congruence either, as this condition applies to specific sets of shapes rather than triangles universally. Hence, the essential aspect of identifying congruent triangles revolves around the equality of their sides, making the method of opposite sides being equal a valid and commonly used approach.