You're reading: Arty Maths

Girih patterns by Joe Bartholomew

Decagonal Dome 2, by Joe Bartholomew

I found Joe Bartholomew’s blog while googling for a fact to do with the 42-gon. In Girih Extended he elaborates on the Islamic girih patterns, which are constructed from translations and rotations of a few polygons, by adding scaled polygons.

In Girih Seven, he used polygons whose internal angles are multiples of $\frac{\pi}{7}$ instead of the $\frac{\pi}{5}$ used in traditional girih.

Girih Seven

I didn’t find the fact I was looking for, but I did find a different one: according to Joe, the 42-gon is also called the tetracontakaidigon.

Site: Joe Bartholomew

2 Responses to “Girih patterns by Joe Bartholomew”

  1. Adam P. Goucher

    The regular 42-gon is constructible by origami, since it is expressible as a product of a power of two, a power of three, and a product of distinct Pierpont primes.


Leave a Reply

  • (will not be published)

$\LaTeX$: You can use LaTeX in your comments. e.g. $ e^{\pi i} $ for inline maths; \[ e^{\pi i} \] for display-mode (on its own line) maths.

XHTML: You can use these tags: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <s> <strike> <strong>