find ∠OQR ∠RST ∠TRQ
∠ROQ = 48

Answer:
We see that SR is a diameter, therefore Δ SRT is right triangle with ∠STR = 90°
∠ROQ, ∠RST and ∠TRQ all intercept the same arc RT
∠ROQ is twice the ∠RST and ∠TRQ as the central angle:
PQ is tangent to circle, therefore: