Answer:
RLS is a straight angle
RLT is an obtuse angle
TLS is an acute angle
TRL is not an angle
TLU is a straight angle
SLU is an obtuse angle
SLT is an acute angle
ULR is an acute angle
and ULS is an obtuse angle
Explanation:
You really just have to look at the angles from either of the straight angles (angles that are 180°) perspective and see of they lean more to make a smaller angle by leaning towards the other end of the angle, or a large one by leaning away from the opposite end.