Hi!

I had a simple problem to solve, sin x = sin 2x, and did it by using the identity sin (2x) = 2 sin (x) cos(x), but what then struck me is that I'm completely clueless how I'd even start solving a problem like sin x = sin (2.4x), or where there essentially are decimals involved and not simple integers.

Are there identities available for these non-integer problems or is the approach completely different?