Question

i need help rewriting this equation with only sin x and cos x : sin 3x - cos x

Answer 1

sin(a+b)= sin(a)cos(b)+sin(b)cos(a)
cos(a+b)= cos(a)cos(b)-sin(a)sin(b)
let a= 2x and b= x
then do it again with a=x and b=x to get rid of the 2x