First degree ode (cosh/sinh)

Homework Statement

$$\frac{dy}{dx} = \frac{cosh x cos y + cosh y sin x}{sinh x sin y - sinh y sin x}$$

I'm really stuck at this one. I don't even know where to start, but I hope that a substitution (ie u = f(x,y)) might be able to put this in a separable form. Any hints please??

1. Hyperbolic cosine/sine identities?

2. Expressing as powers of e?

$$\partial$$D/$$\partial$$y=$$\partial$$N/$$\partial$$x