Pyramids

A pyramid is a three dimensional shape with a polygon as its base and flat triangular faces which meet at a single point. The point at which the triangular faces meet is called the apex. There are different types of pyramid. Let us look at a few.

Triangular Pyramid

This is a pyramid in which the base is a triangle. Each side of the base has one triangular face joined to it. These three triangles meet at the apex. A triangular pyramid has four triangular faces, four vertices and 6 edges. Look at the triangular pyramid below.

(Image by en:User:CYp and used under this creative commons license)

If you cut open a triangular pyramid along the edges, you might get something like this. This is called the net of a triangular pyramid.

Square Pyramid

A square pyramid has a square as its base. Each side of the base has a triangle joined to it. These four triangles meet at the apex. A square pyramid has five faces (one square face and four triangular faces), five vertices and 8 edges.

If you could cut open a square pyramid along the edges, you might get something like this. This is known as the net of a square pyramid.

More pyramids

Look at the picture below. It shows two pyramids. One has a pentagon as its base. it is called a pentagonal pyramid. The other has a hexagon as its base. It is called a hexagonal pyramid.

The pyramid on the left is a pentagonal pyramid and the one on the right is a hexagonal pyramid. How many faces, vertices and edges does each one have?

Note: Other polygons such a heptagon, an octagon, a nonagon or a decagon can be used as the base for a pyramid.