In a unit circle, the radian measure of the central angle is equal to the length of the
Intercepted arc
Radius
Diameter
Circumference

Solution:

We know that the arc is measured using the arc length equation

s = θ r (1)

Where θ is the central angle which is measured in radians

r is the radius

If the unit circle has radius of 1 m length then we understand that arc varies directly proportional to the central angle. 

Therefore, the central angle is equal to the length of the intercepted arc.

In a unit circle, the radian measure of the central angle is equal to the length of the

Summary:
In a unit circle, the radian measure of the central angle is equal to the length of the intercepted arc.