block the entrance.

the center of the base to the vertex is the axis. If the axis is perpendicular to the base, the pyramid is a right pyramid; otherwise it is

an oblique pyramid. A triangular pyramid has a triangular base, a square pyramid has a square base, and so on. If a portion near the

vertex has been cut off, the pyramid is truncated, or referred to as a frustum. The Pyramids of Egypt are tetrahedral, meaning they

have five sides.