BuktikanCos 5x. Sinx +cos x.sin 3x - cos 2x. Sin 4x = 0

Trigonometry.

cos α sin β = 1/2 [sin (α + β) - sin (α - β)]

cos 5x sin x + cos x sin 3x - cos 2x sin 4x
= 1/2 [sin (5x + x) - sin (5x - x)] + 1/2 [sin (x + 3x) - sin (x - 3x)] - 1/2 [sin (2x + 4x) - sin (2x - 4x)]
= 1/2 [sin 6x - sin 4x + sin 4x - sin (-2x) - sin 6x + sin (-2x)]
= 0
Proved.