# Calculus

posted by
**Patrick**
.

Let y(x)=ln(cosh(x)+ sqrt(cosh^2(x)−1))

Find the derivative Dxy=

I don't know what to do with this...

posted by
**Patrick**
.

Let y(x)=ln(cosh(x)+ sqrt(cosh^2(x)−1))

Find the derivative Dxy=

I don't know what to do with this...