The surface of the pyramid S is equal to the sum of the contents of the base Sp and the shell Spl.
The volume of the pyramid is equal to 1/3 of the product of the contents of the base Sp and the height of the pyramid v.
A tetrahedron is the simplest polyhedron, a type of three-dimensional body.
A general tetrahedron is made up of four general triangles.
Body base
Base: triangle – the mantle consists of three isosceles triangles.
A regular tetrahedron is made up of four equal equilateral triangles.
The regular tetrahedron is the 1st Platonic body.
A Platonic solid is a convex polyhedron in which all surfaces are formed by identical regular polygons and the same number of planes always meet at each vertex.
There are five Platonic bodies:
• Regular tetrahedron 
• Regular hexagon 
• Regular octagon 
• Regular dodecahedron 
• Regular icosahedron 