Tetrahedra

thumb|A tetrahedron.

polyhedral number representing a tetrahedron

thumb|Roman caltrop at the Westphalian Museum of Archeology (German: Westfälisches Museum für Archäologie), Herne, North Rhine-Westphalia, Germany

type of structure in coastal engineering

thumb|A Pyraminx slightly turned from the solved position

Tetrahedrane is a hypothetical platonic hydrocarbon with chemical formula and a tetrahedral structure. The molecule would be subject to considerable angle strain and has not been synthesized . However, a number of derivatives have been prepared. In a more general sense, the term tetrahedranes is used to describe a class of molecules and ions with related structure, e.g. white phosphorus.

Platonic solid

In geometry, a disphenoid () is a tetrahedron whose four faces are congruent acute-angled triangles. It can also be described as a tetrahedron in which every two edges that are opposite each other have equal lengths. Other names for the same shape are isotetrahedron, sphenoid, bisphenoid, isosceles tetrahedron, equifacial tetrahedron, almost regular tetrahedron, and tetramonohedron.

thumb|The Pyramorphix in its solved state thumb|right|The Pyramorphix, scrambled

3D symmetry group

shape formed by intersecting four balls

geometric theorem related to tetrahedra

linear stacking of regular tetrahedra

type of die

geometric kite pattern

geometrical shape