Question

Arc AB is One-third of the circumference of a circle. What is the radian measure of the central angle?

StartFraction pi Over 3 EndFraction radians
StartFraction 2 pi Over 3 EndFraction radians
StartFraction 3 pi Over 2 EndFraction radians
3π radians

Answer 1

Arc AB is one-third of the circle, so the central angle is one-third of the full angle 2π radians:

(1/3) · 2π = 2π/3.

Answer: 2π/3 radians.