FP2 Integration Question (hyperbolics)

I've been tossing this question around my head for a while now and come to a dead end. It's just a mini integration but I can't seem to get my head around it. In the chapter for Integration of Hyperbolic functions, the question is:

Find the area of the finite region bounded by the curve with equation x^2 - y^2 = 4

I've tried expressing the equation with y as the subject, then inversing the whole thing to get a term that integrates nicely to an arcosh. I changed the upper limit to sqrt(29) and the lower limit to 0, but 0 gives n error vlue when arcosh comes out, as arcosh(0) isn't valid.

Any thanks would be appreciated