Simple Cross-Sectional Volumes:
Simply integrate, where “f(x) – g(x)” is a side of a shape.

Volumes of Revolution Disks:
Circles that have a thickness, which makes it 3D, AKA have a volume.
Remember, they can also be calculated horizontally.

Volumes of Revolution Washers:
Circles that have a thickness and a hole in the middle, which makes it 3D, AKA have a volume.
Remember, they can also be calculated horizontally.