Answer:
PS must be congruent to RT.
Step-by-step explanation:
In Triangles PTS and RST:
Side: PT is congruent to RS
Side: TS is a corresponding part to both triangles.
For the two triangles to be congruent by the SSS congruence theorem, the third side of the triangles must be congruent.
That is:
Side: PS is congruent to RT.