assuming the derivatives of and , use the quotient rule to find the derivative of
I have no idea how to start this because i dont know what the derivatives are :S
The derivatives of sinh and cosh are very similar to their sin and cos counterparts. They are in fact easier, sinh differentiates to cosh, and cosh differentiates to sinh, you do not have to worry about any minus signs.
As for the quotient rule, here is a link that explains it well.