Let be a regular polygon with sides of length and let , the apex, be a point directly above the center of . A right pyramid is the solid formed by joining the vertices of to and filling in the triangular faces.
The Indian mathematician Aryabhata determined that the volume of any pyramid is , where is the area of the base polygon , using that the inner radius of is .
The slant height is . The base perimeter is , number of sides × side length. The slant surface area is given by .