Question

Rewrite with only sin x and cos x.

cos 3x

A) cos x - 4 cos x sin2x
B) -sin3x + 2 sin x cos x
C) -sin2x + 2 sin x cos x
D) 2 sin2x cos x - 2 sin x cos x

Answer 1

graph one by one and see wich one matches cos 3x

Answer 2

for A
(cos x - 4 cos x sin2x) OR (cos x - 4 cos x sin^2 x) ?