## Is it possible to solve this "hyperbolic functions" problem?

Hi, I've got this problem: I have to write this quantity

Cosh(x)*Cosh(y)

only in function of the quantity

k=Cosech(x)*Cosech(y)

Where for both formula x,y are indipendent real variables.
This could seem a quite easy problem at first sight, but I spent two days between the proprieties of hyperbolic function without any answer.