Archimedean solid

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The rhombicosidodecahedron, one of the Archimedean solids

In geometry, an Archimedean solid is a highly symmetric, semi-regular convex polyhedron composed of two or more types of regular polygons meeting in identical vertices. They are distinct from the Platonic solids, which are composed of only one type of polygon meeting in identical vertices, and from the Johnson solids, whose regular polygonal faces do not meet in identical vertices.

"Identical vertices" are usually taken to mean that for any two vertices, there must be an isometry of the entire solid that takes one vertex to the other. Sometimes it is instead only required that the faces that meet at one vertex are related isometrically to the faces that meet at the other. This difference in definitions controls whether the elongated square gyrobicupola is considered an Archimedean solid or a Johnson solid: it is the unique convex polyhedron that has regular polygons meeting in the same way at each vertex, but that does not have a global symmetry taking every vertex to every other vertex. Based on its existence, Branko Grünbaum (2009) has suggested a terminological distinction in which an Archimedean solid is defined as having the same vertex figure at each vertex (including the elongated square gyrobicupola) while a uniform polyhedron is defined as having each vertex symmetric to each other vertex (excluding the gyrobicupola).

Prisms and antiprisms, whose symmetry groups are the dihedral groups, are generally not considered to be Archimedean solids, despite meeting the above definition. With this restriction, there are only finitely many Archimedean solids. All but the elongated square gyrobicupola can be made via Wythoff constructions from the Platonic solids with tetrahedral, octahedral and icosahedral symmetry.

Origin of name[edit]

The Archimedean solids take their name from Archimedes, who discussed them in a now-lost work. Pappus refers to it, stating that Archimedes listed 13 polyhedra.[1] During the Renaissance, artists and mathematicians valued pure forms and rediscovered all of these forms. This search was almost entirely completed around 1620 by Johannes Kepler,[2] who defined prisms, antiprisms, and the non-convex solids known as the Kepler-Poinsot polyhedra.

Kepler may have also found the elongated square gyrobicupola: at least, he once stated that there were 14 Archimedean solids. However, his published enumeration only includes the 13 uniform polyhedra, and the first clear statement of the gyrobicupola's existence was made in 1905, by Duncan Sommerville.[1]

Classification[edit]

There are 13 Archimedean solids (not counting the elongated square gyrobicupola; 15 if the mirror images of two enantiomorphs, see below, are counted separately).

Here the vertex configuration refers to the type of regular polygons that meet at any given vertex. For example, a vertex configuration of (4,6,8) means that a square, hexagon, and octagon meet at a vertex (with the order taken to be clockwise around the vertex).

Name
(Vertex configuration)
Transparent Solid Net Faces Edges Vertices Point group
truncated tetrahedron
(3.6.6)
Truncated tetrahedron
(Animation)
Truncated tetrahedron.png Truncated tetrahedron flat.svg 8 4 triangles
4 hexagons
18 12 Td
cuboctahedron
(3.4.3.4)
Cuboctahedron
(Animation)
Cuboctahedron.png Cuboctahedron flat.svg  14  8 triangles
6 squares
24 12 Oh
truncated cube
or truncated hexahedron
(3.8.8)
Truncated hexahedron
(Animation)
Truncated hexahedron.png Truncated hexahedron flat.svg 14 8 triangles
6 octagons
36 24 Oh
truncated octahedron
(4.6.6)
Truncated octahedron

(Animation)

Truncated octahedron.png Truncated octahedron flat.png 14 6 squares
8 hexagons
36 24 Oh
rhombicuboctahedron
or small rhombicuboctahedron
(3.4.4.4 )
Rhombicuboctahedron
(Animation)
Small rhombicuboctahedron.png Rhombicuboctahedron flat.png 26 8 triangles
18 squares
48 24 Oh
truncated cuboctahedron
or great rhombicuboctahedron
(4.6.8)
Truncated cuboctahedron
(Animation)
Great rhombicuboctahedron.png Truncated cuboctahedron flat.svg 26 12 squares
8 hexagons
6 octagons
72 48 Oh
snub cube
or snub hexahedron
or snub cuboctahedron
(2 chiral forms)
(3.3.3.3.4)
Snub hexahedron (Ccw)
(Animation)
Snub hexahedron (Cw)
(Animation)
Snub hexahedron.png Snub cube flat.svg 38 32 triangles
6 squares
60 24 O
icosidodecahedron
(3.5.3.5)
Icosidodecahedron
(Animation)
Icosidodecahedron.png Icosidodecahedron flat.svg 32 20 triangles
12 pentagons
60 30 Ih
truncated dodecahedron
(3.10.10)
Truncated dodecahedron
(Animation)
Truncated dodecahedron.png Truncated dodecahedron flat.png 32 20 triangles
12 decagons
90 60 Ih
truncated icosahedron
(5.6.6 )
Truncated icosahedron
(Animation)
Truncated icosahedron.png Truncated icosahedron flat-2.svg 32 12 pentagons
20 hexagons
90 60 Ih
rhombicosidodecahedron
or small rhombicosidodecahedron
(3.4.5.4)
Rhombicosidodecahedron
(Animation)
Small rhombicosidodecahedron.png Rhombicosidodecahedron flat.png 62 20 triangles
30 squares
12 pentagons
120 60 Ih
truncated icosidodecahedron
or great rhombicosidodecahedron
(4.6.10)
Truncated icosidodecahedron
(Animation)
Great rhombicosidodecahedron.png Truncated icosidodecahedron flat.svg 62 30 squares
20 hexagons
12 decagons
180 120 Ih
snub dodecahedron
or snub icosidodecahedron
(2 chiral forms)
(3.3.3.3.5)
Snub dodecahedron (Ccw)
(Animation)
Snub dodecahedron (Cw)
(Animation)
Snub dodecahedron ccw.png Snub dodecahedron flat.svg 92 80 triangles
12 pentagons
150 60 I

Some definitions of semiregular polyhedron include one more figure, the elongated square gyrobicupola or "pseudo-rhombicuboctahedron".[3]

Properties[edit]

The number of vertices is 720° divided by the vertex angle defect.

The cuboctahedron and icosidodecahedron are edge-uniform and are called quasi-regular.

The duals of the Archimedean solids are called the Catalan solids. Together with the bipyramids and trapezohedra, these are the face-uniform solids with regular vertices.

Chirality[edit]

The snub cube and snub dodecahedron are known as chiral, as they come in a left-handed (Latin: levomorph or laevomorph) form and right-handed (Latin: dextromorph) form. When something comes in multiple forms which are each other's three-dimensional mirror image, these forms may be called enantiomorphs. (This nomenclature is also used for the forms of certain chemical compounds).

See also[edit]

Notes[edit]

  1. ^ a b Grünbaum (2009).
  2. ^ Field J., Rediscovering the Archimedean Polyhedra: Piero della Francesca, Luca Pacioli, Leonardo da Vinci, Albrecht Dürer, Daniele Barbaro, and Johannes Kepler, Archive for History of Exact Sciences, 50, 1997, 227
  3. ^ Malkevitch (1988), p. 85

References[edit]

  • Jayatilake, Udaya (March 2005). "Calculations on face and vertex regular polyhedra". Mathematical Gazette 89 (514): 76–81. 
  • Grünbaum, Branko (2009), "An enduring error", Elemente der Mathematik 64 (3): 89–101, doi:10.4171/EM/120, MR 2520469 . Reprinted in Pitici, Mircea, ed. (2011), The Best Writing on Mathematics 2010, Princeton University Press, pp. 18–31 .
  • Williams, Robert (1979). The Geometrical Foundation of Natural Structure: A Source Book of Design. Dover Publications, Inc. ISBN 0-486-23729-X.  (Section 3-9)
  • Malkevitch, Joseph (1988), "Milestones in the history of polyhedra", in Senechal, M.; Fleck, G., Shaping Space: A Polyhedral Approach, Boston: Birkhäuser, pp. 80–92 .
  • Anthony Pugh (1976). Polyhedra: A visual approach. California: University of California Press Berkeley. ISBN 0-520-03056-7.  Chapter 2

External links[edit]