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Example: a retrograde star antiprism with regular star 7/5-gon bases (vertex configuration: 3.3.3.7/5) cannot be uniform. Also, star antiprism compounds with regular star p/q-gon bases can be constructed if p and q have common factors. Example: a star 10/4-antiprism is the compound of two star 5/2-antiprisms.
A pentagrammic antiprism is made of two regular pentagrams and 10 equilateral triangles. In geometry, a prismatic uniform polyhedron is a uniform polyhedron with dihedral symmetry. They exist in two infinite families, the uniform prisms and the uniform antiprisms. All have their vertices in parallel planes and are therefore prismatoids.
In geometry, an n-gonal trapezohedron, n-trapezohedron, n-antidipyramid, n-antibipyramid, or n-deltohedron [3], [4] is the dual polyhedron of an n-gonal antiprism.The 2n faces of an n-trapezohedron are congruent and symmetrically staggered; they are called twisted kites.
In geometry, the hexagonal antiprism is the 4th in an infinite set of antiprisms formed by an even-numbered sequence of triangle sides closed by two polygon caps. Antiprisms are similar to prisms except the bases are twisted relative to each other, and that the side faces are triangles, rather than quadrilaterals .
In 4-dimensional geometry, a uniform antiprismatic prism or antiduoprism is a uniform 4-polytope with two uniform antiprism cells in two parallel 3-space hyperplanes, connected by uniform prisms cells between pairs of faces. The symmetry of a p-gonal antiprismatic prism is [2p,2 +,2], order 8p.
In geometry, a snub polyhedron is a polyhedron obtained by performing a snub operation: alternating a corresponding omnitruncated or truncated polyhedron, depending on the definition. Some, but not all, authors include antiprisms as snub polyhedra, as they are obtained by this construction from a degenerate "polyhedron" with only two faces (a ...
The snub square antiprism (J 85) can be seen as a square antiprism with a chain of equilateral triangles inserted around the middle. The sphenocorona (J 86) and the sphenomegacorona (J 88) are other Johnson solids that, like the square antiprism, consist of two squares and an even number of equilateral triangles.
An example of a molecular species with square prismatic geometry (a slightly flattened cube) is octafluoroprotactinate(V), [PaF 8] 3–, as found in its sodium salt, Na 3 PaF 8. [6] While local cubic 8-coordination is common in ionic lattices (e.g., Ca 2+ in CaF 2 ), and some 8-coordinate actinide complexes are approximately cubic, there are no ...