Polyhedron with eight faces.
A regular octahedron is a regular convex polyhedron in which all of its faces are isometric equilateral triangles. It is one of the five Platonic solids. It has 6 vertices, 12 edges, and 8 faces.
Based on the length \(a\) of the edge, we can calculate the area A and volume V of a regular octahedron: