Question

Prove that sin 3a = 2 sin a - 4sin^3a

Answer 1

Answer:

2 sinA − 1 = 0. ⇒ sinA = 1/2. We know sin 30° = 1/2. So, A = 30°. LHS = sin 3A = sin90° = 1. RHS = 3sinA - 4sin3A. =3 sin30° - 4sin330°.