Step-by-step explanation:
Using sin(a + b) = sin a cos b + cos a sin b
sin(3x) = sin(2x + x) = sin 2x cos x + cos 2x sin x
Using cos(2a) = 1 - 2 sin^2 a
= 2 sin x cos x cos x + (1 - 2sin^2 x) sin x
Using sin^2 a + cos^2 a = 1 ; cos^2 a = 1 - sin^2 a
= 2 sin x(1 - sin^2 x) + sin x - 2 sin^3 x
= 3 sin x - 4 sin^3 x
please give me a brainliest answer
