One radian is defined as the angle from the center of a circle which intercepts an arc equal in length to the radius of the circle. More generally, the magnitude in radians of a subtended angle is equal to the ratio of the arc length to the radius of the circle; that is, , where is the subtended angle in radians, is arc length, and is radius. Conversely, the length of the intercepted arc is equal to the radius multiplied by the magnitude of the angle in radians; that is, .