#### Answer

Part 1: $\angle$RST or $\angle$TSR
Part 2: $\angle$S
Part 3: The angle is greater than 90$^{\circ}$

#### Work Step by Step

Parts 1 and 2: These are the three possible angles. The two listed for part one follow the question's specifications. The one listed for part two follow the question's specifications as well.
Part 3: The diagram clearly shows an obtuse angle, and therefore has a measure greater than 90 degrees.