Answer
Radian measure is a unit that is used to measure an angle. One full circle has a radian measure of $2\pi$ radians.
Work Step by Step
Radian measure is a unit that is used to measure an angle. One full circle has a radian measure of $2\pi$ radians.
If a radius with a length of one unit rotates through an angle of $x$ radians, then the angle subtends an arc length of $x$ units.