Question

When do you use the ring method vs. the cylinder method? And how do you tell if the functions are in terms of x or y? (Calculus)

Answer 1

this is not an easy answer to give quickly, but you can always use both methods

either way, the choice of dx or dy depends on the dependent variable. Using shell and disk method on the same problem illustrates this, for example...

Answer 2

say we want the volume between y=x^2 and y=4 revolved round the x-axis. If we use disk method we can draw in the disks...