So, I know the formula for the disc method is: ...what I'm so confused about is how to fix up when the axis of revolution isn't the x-axis or the y-axis. For example:

http://i52.tinypic.com/nqhp5.jpg

What is the equation to be used when using the disc method to get:

a.) shaded region when revolved to y=8

b.) non-shaded region when revolved to y=8

Thank you in advance!