Question

Prove that (sin 3x/sin x)-(cos 3x/cos x) = 2

Answer 1

You know you posted this twice? I responded on the last one but I guess I will say it one more time.
Combine the fractions.
There will be an identity you can use for the top and the bottom once you have written the left hand side as one fractions.

Answer 2

Have you did that first thing?

Answer 3

Okay, i have already combined it. Then?

Answer 4

you should get
sin3xcosx - cos3xsinx
------------------
sinxcosx