Explanation:
step 1. a diagram is important and can be uploaded. you will get a quicker answer with a diagram
step 2. triangle RST is a right triangle so we can use trigonometry to find <S
step 3. the adjacent side of <S is ST and the hypotenuse is RS so we will use cos
step 4. cosS = adj/hyp = ST/RS = 2.7/4.9
step 5. <S = 56.6° using inverse cos.