Question

How to simplify sin(4x) in terms of sin(x) and cos(x) ?

Answer 1

sin 4 x = 4 ( sin x − 2 sin 3 x ) √ 1 − sin 2 x

explanation: sin 4 x = 2 sin 2 x cos 2 x = 2 × 2 sin x cos x × ( 1 − 2 sin 2

= 4 sin x cos x − 8 sin 3 x cos x