One complete revolution around a circle corresponds to a rotation angle of how many radians?

1. A rotation angle of two pi radians corresponds to an object returning to its starting position after tracing the full circumference, which is one complete revolution. 2. Because the arc length of a full circle is the circumference 2 pi r, dividing by the radius r gives a rotation angle of exactly 2 pi radians for one revolution. 3. Pi radians describes only a half turn, not a full revolution. 4. 360 radians and one radian each describe an amount of rotation far removed from a single full turn, since 360 degrees, not 360 radians, equals one revolution. _Source: OpenStax College Physics (CC BY 4.0), Ch 6 "Uniform Circular Motion and Gravitation", section 6.1 Rotation Angle and Angular Velocity_