A roller on the inclined suface.?

the disk has a m of 20 kg and rests on the smooth inclined surface. one end of spring is attached to the center of the disk and the other end is attached to a roller at A. consequently, the spring rests in the horizontal position when the disk is in equilibrium. if the unstretched length of the spring is 200mm, determine its (total) length when the disk is in equilibrium. neglect the size and weight of the roller.