Volume of Revolution

Volume when rotating about some axis
You can always translate when not revolving around a standard axis
This can result in the volume of a Sphere or cone
2 methods:

Method of Disks

Create many rings perpendicular to the axis of revolution
You create a bunch of washer looking things
So something like this
Becomes this

Sum them all up and it's an Integral

Method of Shells

Basically, make many cylinders parallel to the axis of revolution
The volume of one shell is the area of the rectangle part of the cylinder times $d x$
This
Becomes this
It's an Integral