In trigonometry, the radian is a form of angular measurement. One radian is the angle subtended at the center of a circle by an arc that is equal in length to the radius of the circle. A complete revolution is equal to 2π radians. A radian is equal to degrees. See also Steradian Degree Retrieved from "https://math.wikia.org/wiki/Radian?oldid=20962" Categories: Trigonometry Community content is available under CC-BY-SA unless otherwise noted.