# Homework Help: First degree ode (cosh/sinh)

1. May 13, 2009

### bigevil

1. The problem statement, all variables and given/known data

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

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?

2. May 13, 2009

### Billy Bob

Is there a typo? It's almost exact. The sin x in the numerator looks out of place.

3. May 13, 2009

### TaiwanCountry

This is an exact equation.

dy/dx = Numerator/Denominater

D dx - N dy =0

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

u (nearly)=D dx + N dy