Dodecagram

Source: Wikipedia, the free encyclopedia.
Regular dodecagram
Dual polygonself

In

turning number
of 5). There are also 4 regular compounds {12/2}, {12/3}, {12/4}, and {12/6}.

Regular dodecagram

There is one regular form: {12/5}, containing 12 vertices, with a

turning number of 5. A regular dodecagram has the same vertex arrangement as a regular dodecagon
, which may be regarded as {12/1}.

Dodecagrams as regular compounds

There are four regular dodecagram

squares, the third is a compound of four triangles, and the fourth is a compound of six straight-sided digons. The last two can be considered compounds of two compound hexagrams
and the last as three compound tetragrams.

  • 2{6}
    2{6}
  • 3{4}
    3{4}
  • 4{3}
    4{3}
  • 6{2}
    6{2}

Dodecagrams as isotoxal figures

An

isotoxal polygon
has two vertices and one edge type within its symmetry class. There are 5 isotoxal dodecagram star with a degree of freedom of angles, which alternates vertices at two radii, one simple, 3 compounds, and 1 unicursal star.

Isotoxal dodecagrams
Type Simple Compounds Star
Density
1 2 3 4 5
Image
{(6)α}

2{3α}

3{2α}

2{(3/2)α}

{(6/5)α}

Dodecagrams as isogonal figures

A regular dodecagram can be seen as a quasitruncated hexagon, t{6/5}={12/5}. Other isogonal (

vertex-transitive
) variations with equally spaced vertices can be constructed with two edge lengths.


t{6}

t{6/5}={12/5}

Complete graph

Superimposing all the dodecagons and dodecagrams on each other – including the degenerate compound of six digons (line segments), {12/6} – produces the complete graph K12.

K12
black: the twelve corner points (nodes)

red: {12} regular dodecagon
green: {12/2}=2{6} two hexagons
blue: {12/3}=3{4} three squares
cyan: {12/4}=4{3} four triangles
magenta: {12/5} regular dodecagram
yellow: {12/6}=6{2} six digons

Regular dodecagrams in polyhedra

Dodecagrams can also be incorporated into

uniform polyhedra. Below are the three prismatic uniform polyhedra
containing regular dodecagrams (there are no other dodecagram-containing uniform polyhedra).

  • Dodecagrammic prism
    Dodecagrammic prism
  • Dodecagrammic antiprism
    Dodecagrammic antiprism
  • Dodecagrammic crossed-antiprism
    Dodecagrammic crossed-antiprism

Dodecagrams can also be incorporated into star tessellations of the Euclidean plane.

Dodecagram Symbolism

The twelve-pointed star is a prominent feature on the ancient Vietnamese Dong Son drums

Dodecagrams or twelve-pointed stars have been used as symbols for the following:

See also

References

  1. ^ γραμμή, Henry George Liddell, Robert Scott, A Greek-English Lexicon, on Perseus
  • Weisstein, Eric W. "Dodecagram". MathWorld.
  • .
  • Grünbaum, B.; Polyhedra with Hollow Faces, Proc of NATO-ASI Conference on Polytopes ... etc. (Toronto 1993), ed T. Bisztriczky et al., Kluwer Academic (1994) pp. 43–70.
  • (Chapter 26. pp. 404: Regular star-polytopes Dimension 2)