Question

What is the arc length of an angle of pi/3 radians formed on the unit circle

Answer 1

Rule:

arc length along circle = (radius) * (angle in radians)

Answer 2

the unit circle has a radius of 1 unit

so for the unit circle

arc length along circle = (radius) * (angle in radians)
arc length along circle = (1) * (angle in radians)
arc length along circle = angle in radians

which means that an angle like pi/4 radians cuts off an arc of length pi/4 units