Area between to crossing cylinders

Hi Everyone.

I am trying to calculate the area between two cylinders, but i am not sure how to do this. Are there any of you guys that can help?

Maybe if it is possible to plot the area, that would be great.

The area i would like to calculate and plot:

I have attached a mathcad file, where i have plotted the two cylinders.

Thank you for your help.

Kind regards

Niels.