Prove that : Cos3 theta + 2cos5 theta + cos7 theta / costheta + 2cos3 theta + cos 5 theta= cos 2 theta - sin2 theta*tan3 theta
Prove that : Cos3 theta + 2cos5 theta + cos7 theta / costheta + 2cos3 theta + cos 5 theta= cos 2 theta - sin2 theta*tan3 theta