Answer: okay me learning this right now so okay
Step-by-step explanation: I worked on the same problem and got it right last time!
Given the major arc and the minor arc share the same chord, the angle RST will be:
∠RST=1/2∠RHT
∠RHT=1/3π=1/3×180=60
hence
∠RST=1/2×60=30°
Answer: 30°