How do you find the base of a square pyramid?

The base of square pyramid is a square, as you may have guessed. If you measure one side of the square base, you'll have discovered the length of a side of the base. A side squared (a side times a side) will give you the area of the base of a square pyramid. If you have the area of the base, you can find the length of a side of the base by finding the square root of the area of the base.

In the case of a square pyramid, if you are given the length of a side and either a vertex angle or the angle between the base and a side, you'll have an isosceles triangle to deal with. (There are four isosceles triangles that make up the faces of the square pyramid, as you probably figured out.) This involves a bit of trigonometry, and there are some other questions here that will help you figure that out.