Question

Rewrite with only sin x and cos x.
sin(3x)-cos x

Answer 1

sin(3x)= sin(2x+x) =sin(2x)cos(x)+sin(x)cos(2x)
= [2sin(x)cos(x)]*cos(x) + {sin(x) [2cos^2(x)-1]}
=2sin(x) *cos^2(x)+ 2sin(x)*cos^2(x)-sin(x)
=4sin(x)cos^2(x)-sin(x)-cos(x) ,the last cos(x) from the question
I hope I did not get anything wrong while typing, but anyways the idea still the same

Answer 2

Thank you

Answer 3

you are welcome :)