The base is the same as the top, and also in-between

It has one curved side

Because it has a curved surface it is not a polyhedron.

And for reference:

Surface Area = 2 × π × r × (r+h)

Surface Area of One End = π × r^{2}

Surface Area of Side = 2 × π × r × h

Volume = π × r^{2 }× h

Instructions: In "spin" mode it freely spins and will respond to your mouse. In "drag" mode it stops spinning and you can use your mouse to move it. If you cannot see the animation at all, you will need to install "Flash Player".

An object shaped like a cylinder is said to be cylindrical

Volume of a Cylinder

Just multiply the area of the circle by the height of the cylinder:

Area of the circle: π × r^{2}

Height: h

Volume = Area × Height = π × r^{2 }× h

There is an easy way to remember:

Imagine you just cooked a pizza.

The radius is "z", and the thickness "a" is the same everywhere ... what is the volume?

Answer: pi × z × z × a

(we would normally write "pi" as π, and z × z as z^{2}, but you get the idea!)

It Doesn't Have to Be Circular

Usually when we say Cylinder we mean a Circular Cylinder, but you can also have Elliptical Cylinders, like this one:

You can even have stranger cylinders: if the cross-section is curved and is the same from one end to the other, then it will still be a cylinder.