1 radian is the angle subtended by an arc of length r where r is the radius of the circle. Since there are 2πradiuses in a circle, then there are 2 π radians in 360°The angular displacement of an object is the angle in radians through which an object turns or is displaced. It is given the symbol θSince the object turns through an angle of 2π/T radians every second, at time t seconds the object turns through an angle of (2π/T)t or 2πt/T radians. This is the angular displacement at time t.