Hyperbolic Functions

**Beard** · October 6th 2009, 10:15 AM

Hi
I'm new to hyperbolic functions so I'm a bit stuck on two problems which may seem easy. I don't know where to start. Any help would be greatly appreciated.

Show from the definitions of $\sinh(x)$ and $\cosh(x)$ that:

a) $cosh(2x) = 2\cosh^2(x) - 1$

and

b) $\sinh(x + y) = \sinh(x)\cosh(y) + \cosh(x)\sinh(y)$

P.S sorry if this is in the wrong area but I couldn't see any that were obviously for it.