Polyhedron with four faces.

The faces of all tetrahedra are triangles.

### Properties

- A tetrahedron is a pyramide with a triangular base.
- A tetrahedron has 4 vertices, 6 edges and 4 triangular faces.
- If the tetrahedron is a regular tetrahedron, then its four faces are congruent equilateral triangles.
- A tetrahedron with three right angles can be obtained from a cube or a right rectangular prism. It is called a trirectangular tetrahedron.

### Formula

The following formulas can be used to calculate the volume *V* and the area *A* of a regular tetrahedron as a function of the edge length *a*:

*V*= \(\dfrac{\sqrt{2}}{12}\)\(a^{3}\)*A*= \(\sqrt{3}\)\(a^{2}\)