Apologies, I'm a bit rusty on my trig. I am trying to manipulate the LHS side of the equation below to arrive at the RHS.
$$2 \sin(x) \cos(n x) = \sin((n + 1) x) - \sin((n - 1) x)$$
I've tried using the double angle formula to rewrite the cos(nx) but I'm not getting anywhere with it.
Thanks in advance.