what is the shape of each face of a tetrahedron
Tetrahedron In geometry, a tetrahedron (plural: tetrahedra or tetrahedrons), also known as a triangular pyramid, is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. The tetrahedron is the simplest of all the ordinary convex polyhedra and the only one that has fewer than 5 faces.[1]
Pyramid (geometry) When unspecified, a pyramid is usually assumed to be a regular square pyramid, like the physical pyramid structures. A triangle-based pyramid is more often called a tetrahedron.
Hermitian matrix The diagonal elements must be real, as they must be their own complex conjugate.
Dodecagon In geometry, a dodecagon or 12-gon is any twelve-sided polygon.