Hi,

On my Notes of problem regarding surface area of revolution

There is a Step

Cosh2(x/c) integrating this

In next step it written as (c/2)sinh2(x/c)

The identity used is integ{cos2x} = sin2x/2

But I can't apply this one in solving that step.

I want to know how the "c" in (c/2) came on integrating

Please have a look at this !!