3 cos 72 degrees - 4 (sin to the power of 3) 18 degrees = cos 36 degrees Share with your friends Share 1 Varun.Rawat answered this LHS = 3 cos 72° - 4 sin318°=3 cos90°-18° - 4 sin318°=3 sin 18° - 4 sin318°=sin 3×18° as, sin 3A = 3 sin A - 4 sin3A= sin 54°=sin 90°-36°=cos 36°=RHS 3 View Full Answer
