tetraedër

A tetrahedron is a polyhedron composed of four triangular faces, six straight edges, and four vertex corners. It is the simplest of all the regular convex polyhedra, and the simplest of all the three-dimensional faces. The name "tetrahedron" comes from the Greek words "tetra" meaning four and "hedra" meaning seat or face.

A tetrahedron is a type of pyramid with a triangular base. If all four faces are equilateral triangles, it is called a regular tetrahedron. In this case, all edges are of equal length, and all angles are equal. A regular tetrahedron is one of the five Platonic solids.

Tetrahedra have various applications in geometry and other fields. They are used in the construction of geodesic domes and in crystallography. The shape of a tetrahedron is also important in chemistry, as many molecules have a tetrahedral structure, such as methane. The volume of a tetrahedron can be calculated using a specific formula, and its properties have been studied for centuries. Understanding the geometry of tetrahedra is fundamental in areas like solid geometry and computational geometry.