Answer:
77°
Step-by-step explanation:
Find the diagram atached
From the figure
m<T = 1/2(arcRU - arcSU)
m<T = 1/2(119-arcSU)
21 = 1/2(119-arcSU)
21*2 = 119-arcSU
42 = 119-arcSU
arcSU = 119 - 42
arcSU = 77degrees
Hence the meaasure of arcSU is 77degrees
B.77
