Definition:Tetrahedron/Apex

Definition

 * Tetrahedron.png

One of the vertices of a tetrahedron can be distinguished from the others, and identified as being the apex of the tetrahedron.

In the above diagram, $D$ is the apex.

As all faces of a tetrahedron are triangular by definition, it follows that all its vertices are the common point of three triangles.

Therefore is qualitatively immaterial which vertex is thus chosen.

This definition is compatible with the definition of the apex of a general pyramid.

Also known as
The apex of a tetrahedron is seen in some sources (for example ) as vertex.

Also see

 * Definition:Base of Tetrahedron