Pentagram

Date: 12/08/2001 at 13:09:15
From: Stephanie Shipwash
Subject: Polygons

Is a 5-pointed star (on a flag), a decagon, or just 5 triangles?

Thanks,
Stephanie

Date: 12/08/2001 at 13:18:20
From: Doctor Sarah
Subject: Re: Polygons

Hi Stephanie - thanks for writing to Dr. Math.

See George Hart's Web page on Pentagrams:

   http://www.georgehart.com/virtual-polyhedra/pentagram.html   

"Pentagrams are "five-pointed stars." They are regular polygons with 
five vertices and five edges; that's all. The sides just happen to 
cross each other at five points of intersection which outline the 
small interior pentagon, but those are not vertices and the smaller 
segments are not complete sides. Mathematically, the pentagram is 
special for being the simplest nonconvex regular polygon."

- Doctor Sarah, The Math Forum
  http://mathforum.org/dr.math/