## quasi-regular polyhedronA polyhedron that consists of two sets of regular polygons, m-sided and
n-sided respectively, and is constructed so that each polygon in
one set is surrounded by members of the other set. There are three convex
quasiregular solids: the cuboctahedron (m = 3,
n = 4), the icosidodecahedron (m = 3,
n = 5), and the octahedron (m = n
= 3). In each case four faces meet at each vertex in the cyclic order
(m, n, m, n). Because of this, these
polyhedra have some special properties, one of which is that their edges
form a system of great circles. The
edges of the octahedron form three squares;
the edges of the cuboctahedron form four hexagons,
and the edges of the icosidodecahedron form six decagons.
Among the nonconvex polyhedra are two examples of type (m, n,
m, n): the dodecadodecahedron (m
= 5, n = 5/2) and the great icosidodecahedron
(m = 3, n = 5/2), which can be made by truncating the
Kepler-Poinsot polyhedra at
their edge midpoints. There are also three nonconvex examples of type (m,
n, m, n, m, n): the small
triambic icosidodecahedron (m=3, n=5/2), the
triambic dodecadodecahedron (m = 5/3, n =
5), and the great triambic icosidodecahedron (m
= 3, n = 5). Finally, there is a group of nine "hemihedra," in
which some faces pass through the polyhedron's center. These hemi faces
each cut a sphere into two hemispheres. ## Related category• SOLIDS AND SURFACES | |||||

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