The two triangles have corresponding, congruent sides. Side QR corresponds to and is congruent to MN as denoted by the single hash mark. Sides QS and MP are corresponding and congruent sides as denoted by the three hash marks. Sides RS and NP are corresponding, congruent sides as denoted by the two hash marks. Therefore, as the SSS postulate states, if three sides in one triangle are corresponding, congruent sides to another triangle, the two triangles are congruent. In both triangles, the three corresponding sides are congruent; therefore, the triangles are congruent.
