<P> This formula only applies for n = 2, 3, 4 and 5; and it also covers the case n = 6, for which the volume equals zero (i.e., the pyramid height is zero). </P> <P> The surface area of a pyramid is A = B + P L 2 (\ displaystyle A = B+ (\ tfrac (PL) (2))), where B is the base area, P is the base perimeter, and the slant height L = h 2 + r 2 (\ displaystyle L = (\ sqrt (h ^ (2) + r ^ (2)))), where h is the pyramid altitude and r is the inradius of the base . </P> <P> A 2 - dimensional pyramid is a triangle, formed by a base edge connected to a noncolinear point called an apex . </P> <P> A 4 - dimensional pyramid is called a polyhedral pyramid, constructed by a polyhedron in a 3 - space hyperplane of 4 - space with another point off that hyperplane . </P>

What has one circular base and one vertex