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The compounds of ten octahedra UC15 and UC16 are two uniform polyhedron compounds. They are composed of a symmetric arrangement of 10 octahedra, considered as triangular antiprisms, aligned with the axes of three-fold rotational symmetry of an
icosahedron In geometry, an icosahedron ( or ) is a polyhedron with 20 faces. The name comes and . The plural can be either "icosahedra" () or "icosahedrons". There are infinitely many non- similar shapes of icosahedra, some of them being more symmetrica ...
. The two compounds differ in the orientation of their octahedra: each compound may be transformed into the other by rotating each octahedron by 60 degrees.


Cartesian coordinates

Cartesian coordinates A Cartesian coordinate system (, ) in a plane is a coordinate system that specifies each point uniquely by a pair of numerical coordinates, which are the signed distances to the point from two fixed perpendicular oriented lines, measured in t ...
for the vertices of this compound are all the cyclic permutations of : (0, ±(τ−1 + 2''s''τ), ±(τ − 2sτ−1)) : (±( − ''s''τ2), ±( + ''s''(2τ − 1)), ±( + ''s''τ−2)) : (±(τ−1 − ''s''τ), ±(τ + ''s''τ−1), ±3''s'') where τ = (1 + )/2 is the golden ratio (sometimes written φ) and ''s'' is either +1 or −1. Setting ''s'' = −1 gives UC15, while ''s'' = +1 gives UC16.


See also

* Compound of three octahedra * Compound of four octahedra * Compound of five octahedra * Compound of twenty octahedra


References

*. Polyhedral compounds {{polyhedron-stub