Answer:
∠ 4 = 71.5°
Step-by-step explanation:
The measure of the chord- chord angle 4 is half the sum of the measures of the arcs intercepted by the angle RU and its vertical angle ST, that is
∠ 4 = [tex]\frac{1}{2}[/tex] ( RU + ST ) = [tex]\frac{1}{2}[/tex] ( 92 + 51)° = [tex]\frac{1}{2}[/tex] × 143° = 71.5°
