Triangle Congruence from Rigid Motions Practice Test

Triangle $$PQR$$ with vertices $$P(3, 4)$$, $$Q(7, 2)$$, $$R(5, 8)$$ is congruent to triangle $$STU$$. If the congruence can be established through rigid motions, but triangle $$STU$$ has vertices $$S(-4, 3)$$, $$T(-2, 7)$$, $$U(-8, 5)$$, what must be verified to confirm the triangles are indeed congruent?

Triangle $$RST$$ is congruent to triangle $$UVW$$ with the correspondence $$R \leftrightarrow U$$, $$S \leftrightarrow V$$, $$T \leftrightarrow W$$. If a $$270°$$ counterclockwise rotation about point $$P$$ maps triangle $$RST$$ onto triangle $$UVW$$, which statement about the angle measures is necessarily true?