Answer:
sin 3x - cos x = 3 (sin x)(cos x)(cos x) -(sin x)(sin x)(sin x) -cos x
Step-by-step explanation:
sin 3x - cos x
This uses Trig Identities.
sin 3x = sin (x + x + x) = sin (x+x)*cos x + cos (x + x) sin x
= 2sinxcosx * cos x + [ (cos x)(cos x) -(sin x)(sin x) ] (sin x)
sin 3x - cos x = 2sinxcosx * cos x + [ (cos x)(cos x) -(sin x)(sin x) ] (sin x) -cos x
sin 3x - cos x = 2sinxcosx * cos x + sinx (cos x)(cos x) -(sin x)(sin x)(sin x) -cos x
sin 3x - cos x = 3 sinx cosx * cos x -(sin x)(sin x)(sin x) -cos x
sin 3x - cos x = 3 (sin x)(cos x)(cos x) -(sin x)(sin x)(sin x) -cos x
