Why is a Prism like a Cylinder?

Try increasing the number of sides:

Yes! The prism starts to look like a cylinder!

As we add more and more sides, the polygon base gets closer and closer to a circle.

In fact, we can think of a cylinder as a prism with an infinite number of sides.

Also try moving points A and B.

Volume

The volume formulas are the same:

V = (Base Area) × Height

For a circular cylinder the base area is πr² (where r is radius) so we get:

Volume of Circular Cylinder = (πr²) × Height

For a square prism the base area is s² (where s is side length) so we get:

Volume of Square Prism = (s²) × Height

For any prism we just have to work out the base area then multiply by height.

Right vs Oblique

And it doesn't matter if it is right (ends are perfectly aligned) or oblique (slanted), the volume formula still works, but remember:

The height is at right angles to the base!