Icosihenagon

Icosihenagon
Rank	2
Type	Regular
Notation
Coxeter diagram	x21o ()
Schläfli symbol	{21}
Elements
Edges	21
Vertices	21
Vertex figure	Dyad, length 2cos(π/21)
Measures (edge length 1)
Circumradius	${\frac {1}{2\sin {\frac {\pi }{21}}}}\approx 3.35475$
Inradius	${\frac {1}{2\tan {\frac {\pi }{21}}}}\approx 3.31728$
Area	${\frac {21}{4\tan {\frac {\pi }{21}}}}\approx 34.83147$
Angle	${\frac {19\pi }{21}}\approx 162.85714^{\circ }$
Central density	1
Number of external pieces	21
Level of complexity	1
Related polytopes
Army	Icosihenagon
Dual	Icosihenagon
Conjugate	5 total
Abstract & topological properties
Flag count	42
Euler characteristic	0
Orientable	Yes
Properties
Symmetry	I2(21), order 42
Flag orbits	1
Convex	Yes
Nature	Tame

The icosihenagon is a polygon with 21 sides. A regular icosihenagon has equal sides and equal angles.

Stellations

• 2-icosihenagram
• 3-icosihenagram (compound of 3 heptagons)
• 4-icosihenagram
• 5-icosihenagram
• 6-icosihenagram (compound of 3 heptagrams)
• 7-icosihenagram (compound of 7 triangles)
• 8-icosihenagram
• 9-icosihenagram (compound of 3 great heptagrams)
• 10-icosihenagram

External links

• Bowers, Jonathan. "Regular Polygons and Other Two Dimensional Shapes".