Prove that:
sin 4A = 4 sin A cos3 A - 4 cos A sin3 A
LHS = sin 4A
= sin 2.2A
= 2 sin 2A cos 2A
= 2(2 sin A cos A). (cos2A−sin2A)
= 4 sin A cos3 A - 4 sin3 A cos A
= RHS.
Prove Prove the formation of image on a plane mirror