三角錐 正三角錐
A "polyhedron":http://en.wikipedia.org/wiki/Polyhedron composed of four [[triangle|triangular]] faces. If all four faces are equilateral triangles, the tetrahedron is regular. Also known as a triangular [[pyramid (geometry)|]].

* !asset #20875379

A compound of two regular tetrahedra is called a [[stellated octahedron]].

h4. External links
* "George Hart: Virtual polyhedra compounds":http://www.georgehart.com/virtual-polyhedra/compounds-info.html
* "Wikipedia: Tetrahedron":https://en.wikipedia.org/wiki/Tetrahedron
* "Wolfram MathWorld: Regular Tetrahedron":https://mathworld.wolfram.com/RegularTetrahedron.html
tetrahedron