Four sides

In geometry, a solid shape with triangular side-faces meeting at a common vertex (point) and with a polygon as its base. The volume V of a pyramid is given by V = 1/3Bh, where B is the area of the base and h is the perpendicular height.

Pyramids are generally classified by their bases. For example, the Egyptian pyramids have square bases, and are therefore called square pyramids. A triangular pyramid is also known as a tetrahedron (‘four sides’).