Regular dodecahedron
| Regular dodecahedron | |
|---|---|
| Type | Platonic solid, Truncated trapezohedron, Goldberg polyhedron |
| Faces | 12 regular pentagons |
| Edges | 30 |
| Vertices | 20 |
| Symmetry group | icosahedral symmetry |
| Dihedral angle (degrees) | 116.565° |
| Dual polyhedron | regular icosahedron |
| Properties | convex, regular |
| Net | |
A regular dodecahedron or pentagonal dodecahedron is a dodecahedron (a polyhedron with 12 faces) composed of regular pentagonal faces, three meeting at each vertex. It is one of the Platonic solids, described in Plato's dialogues as the shape of the universe itself. Johannes Kepler used the dodecahedron in his 1596 model of the Solar System. However, the dodecahedron and other Platonic solids had already been described by other philosophers since antiquity.
The regular dodecahedron is a truncated trapezohedron because it is the result of truncating axial vertices of a pentagonal trapezohedron. It is also a Goldberg polyhedron because it is the initial polyhedron to construct new polyhedra by the process of chamfering. It has a relation with other Platonic solids, one of them is the regular icosahedron as its dual polyhedron. Other new polyhedra can be constructed by using a regular dodecahedron.
The regular dodecahedron's metric properties and construction are associated with the golden ratio. The regular dodecahedron is featured in some artistic and narrative works. Some toys and artifacts are also shaped like regular dodecahedra, including the Roman dodecahedron. Regular dodecahedra can also be found in nature and supramolecules, as well as the shape of the universe. The skeleton of a regular dodecahedron can be represented as the graph called the dodecahedral graph, a Platonic graph. Its property of the Hamiltonian, a path that visits all of its vertices exactly once, can be found in a toy called icosian game.