Respuesta :

25 degrees is the correct answer

Answer: The answer in 20° in USA TestPrep

Step-by-step explanation:

S=2πr× n°/360°

n°=360s/2πr= 360(64π/9)/2π(4)=320

This,∆H=360-320=40

Then, ∆RST=1/2 ∆H= 1/2(40)=20