Question

Which postulate or theorem can be used to prove that PQR is PST?

Answer 1

Presuming that QR and ST are parallel, the following must be true:

∠S = ∠Q

∠T = ∠R

∠P = ∠P (They have 1 common angle.)

With this relationship of angles, the triangle must be similar under AA Similarity Postulate.

There, the 1st option is the answer.