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 $\displaystyle \sinh(x)$ and $\displaystyle \cosh(x)$ that:

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

and

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

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