I didn't learn how to do this in my class, and the examples in my book do not apply to this type of problem.
To make a rectangular trough, you bend the sides of a 32-inch wide sheet of metal to obtain the cross section pictured below. Find the dimensions of the cross section with the maximum area. (this will result in the trough with the largest possible volume).
I don't really know how to proceed. I know that I need to use derivatives to solve this, but I can't seem to get started