I made this years ago — in 2010 — and just found it today, on Facebook. That was two years before this blog started. I like finding such “lost works,” but it doesn’t happen often these days.

# Tag Archives: nonagon

# Four Polyhedra Featuring Enneagons

Enneagons are also called nonagons; they are polygons with nine sides. I used *Stella 4d* to make these four rotating polyhedra, and you may try this program for yourself at http://www.software3d.com/Stella.php.

# Tessellation of Blue Triangles and Yellow Concave Pentagons

Alternately, this can be seen as a tessellation of blue diconcave hexagons and yellow triconcave enneagons. Which do you see?

# Two Polyhedra, Each Featuring Enneagons and Octagons

I used *Stella 4d: Polyhedron Navigator* to make these. You can try it for yourself at http://www.software3d.com/Stella.php.

# A Polyhedron Made of Enneagons and Pentagons

This polyhedron has 20 enneagons and 12+60=72 pentagons (of two types) as faces. I made it using *Stella 4d*, which is available at http://www.software3d.com/Stella.php.

## Tessellation Featuring Regular Enneagons, Regular Hexagons, and Isosceles Triangles

### Image

## Tessellation Featuring Regular Enneagons and Hexaconcave, Equilateral Dodecagons

### Image

# Three Convex Polyhedra with Tetrahedral Symmetry, Each Featuring Four Regular Enneagons

In addition to the four regular enneagons, the polyhedron above also has rhombi and isosceles triangles as faces. The next one, however, adds equilateral triangles, instead, to the four regular enneagons, along with trapezoids and rectangles.

Only the last of these three truly deserves to be called a symmetrohedron, in my opinion, for both its hexagons and enneagons are regular. Only the “bowtie trapezoid” pairs are irregular.

All three of these polyhedra were created using software called* Stella 4d: Polyhedron Navigator*, which I use frequently for the blog-posts here. You can try it for free at this website.