Final answer:
The congruence criterion that justifies the statement △PQR≅△STR is SSS (Side-Side-Side).
Step-by-step explanation:
To prove that △PQR≅△STR, we need to use a congruence criterion. The congruence criterion that justifies this statement is SSS (Side-Side-Side). This criterion states that if all three sides of one triangle are congruent to the corresponding sides of another triangle, then the two triangles are congruent.
In this case, we need to show that PR=TS, QR=SR, and PQ=ST. Once we prove that all three pairs of corresponding sides are congruent, we can conclude that the triangles are congruent.