Rhombic dodecahedron
The rhombic dodecahedron is a
convex polyhedron with 12
rhombic faces. Multiples of it can be stacked to fill a space much like
hexagons fill a plane; the cells in a
honeycomb have a shape similar to the rhombic dodecahedron cut in half.
It is the polyhedral
dual of the
cuboctahedron and a zonohedron. The long diagonal of each face is exactly
v2 times the length of the short diagonal, so that the acute angles on each face measure 2 tan−1, or approximately 70.53.
Being the dual of an
Archimedean polyhedron, the rhombic dodecahedron is
face-uniform, meaning the
symmetry group of the solid acts transitively on the set of faces.
Encyclopedia
The
rhombic dodecahedron is a
convex polyhedron with 12
rhombic faces. Multiples of it can be stacked to fill a space much like
hexagons fill a plane; the cells in a
honeycomb have a shape similar to the rhombic dodecahedron cut in half.
It is the polyhedral
dual of the
cuboctahedron and a zonohedron. The long diagonal of each face is exactly
v2 times the length of the short diagonal, so that the acute angles on each face measure 2 tan
−1, or approximately 70.53°.
Being the dual of an
Archimedean polyhedron, the rhombic dodecahedron is
face-uniform, meaning the
symmetry group of the solid acts transitively on the set of faces. In elementary terms, this means that for any two faces A and B there is a
rotation or reflection of the solid that leaves it occupying the same region of space while moving face A to face B. The rhombic dodecahedron is also somewhat special in being one of the nine
edge-uniform convex polyhedra, the others being the five
Platonic solids, the
cuboctahedron, the
icosidodecahedron and the
rhombic triacontahedron.
The rhombic dodecahedron can be used to
tessellate 3-dimensional space. This tessellation can be seen as the
Voronoi tessellation of the
face-centred cubic lattice.
Honeybees use the geometry of rhombic dodecahedra to form
honeycomb from a tessellation of cells each of which is a hexagonal prism capped with half a rhombic dodecahedron.
The rhombic dodecahedron forms the hull of the vertex-first projection of a
tesseract to 3 dimensions. There are exactly two ways of decomposing a rhombic dodecahedron into 4 congruent
parallelepipeds, giving 8 possible parallelepipeds. The 8 cells of the tesseract under this projection map precisely to these 8 parallelepipeds.
Cartesian coordinates
The eight vertices where three faces meet at their obtuse angles have
Cartesian coordinates
The six vertices where four faces meet at their acute angles are given by the permutations of
See also
External links
- – from MathWorld
- – The Encyclopedia of Polyhedra
- – make a rhombic dodecahedron calendar without glue