Two Symmetrohedra Which Each Feature Four Regular Enneagons

This symmetrohedron has the following faces: four regular enneagons, four equilateral triangles, and twelve isosceles triangles with vertex angles of 43.5686 degrees. Its net is shown below.

If this polyhedron is stellated once, the result is another symmetrohedron — one with four enneagonal faces, as well as twelve kites. The angles in the kites are 116.762, 99.8348, 43.5686, and 99.8348 degrees, and their side lengths are in a 1:2.2946 ratio.

Finally, here is a net for this kite-and-enneagon solid.

I used Stella 4d: Polyhedron Navigator to make everything you see here. If you’d like to try this software for yourself, a free trial download is available at http://www.software3d.com/Stella.php.

A Polyhedral Journey, Starting With the Truncated Tetrahedron

Here’s the truncated tetrahedron. It is the simplest of the Archimedean solids.

I decided to “take a walk” with this polyhedron. First, I used Stella 4d (available here) to make the compound of this solid and its dual, the Catalan solid named the triakis tetrahedron.

Next, also using Stella (as I’m doing throughout this polyhedral journey), I formed the convex hull of this polyhedron — a solid made of kites and rhombi.

For the next polyehdron on this journey, I formed the dual of this convex hull. This solid is a symmetrohedron, featuring four regular hexagons, four equillateral triangles, and twelve isosceles triangles.

Next, I used a function of this program called “try to make faces regular.” Some this function works, and sometimes it doesn’t, if it isn’t mathematically possible — as it the case here, where the only thing that remained regular was the equilateral triangles. The hexagons in the resulting solid are equilateral, but not equiangular.

The next thing I did was to examine the dual of this latest polyhedron — another solid made of kites and rhombi, but with broader rhombi and narrower kites.

I then started stellating this solid. The 16th stellation was interesting, so I made a virtual model of it.

Stellating this twice more formed the 18th stellation, which turned out to be a compound of the cube and a “squished” version of the rhombic dodecahedron. This is when I decided that this particular polyhedral journey had come to an end.

Tessellation of Regular Hexagons, Convex Pentagons, and Kites

Image

Happy Perfect-Square New Year 2025

As I write this, the new year, 2025, has already come to parts of the world. It arrives here, where we’re on Chicago time, in about four and a half hours. This new year is the first perfect-square year since 1936, and there won’t be another one until 2116.

Since 45 = (9)(5) = (3^2)(5), and 2025 is the square of that, the prime number factorization of the new year is (3^4)(5^2).

Happy New Year to all!

The 35th Stellation of the Truncated Dodecahedron

I made this using Stella 4d: Polyhedron Navigator, which you can try for yourself, free, at http://www.software3d.com/Stella.php.

Twenty Tetrahedra, Attached to the Vertices of a Dodecahedron

I made this using Stella 4d: Polyhedron Navigator, which you can try for free at http://www.software3d.com/Stella.php.

Boycott Amazon — Until the Strike is Resolved

Amazon workers are on strike against Amazon, for unfair labor practices, in multiple locations across the USA. While the strike continues, it is important that we support these workers and their unions, by doing these three things:

  1. Don’t buy anything from Amazon.
  2. Don’t buy Amazon’s stock.
  3. If you already own shares of Amazon, sell them.

Since Amazon does most of its business on the Internet, the concept of a “picket line” has to be updated for the 21st Century. If you go on the Internet and buy anything from Amazon while the strike is in progress, you’re crossing this picket line.

How long should we boycott Amazon? At least until the strike is over — no matter how long that takes. Solidarity among and between unions and workers is essential . . . because if we don’t support each other, no one else will.

Thomas Jefferson Visits the Bagel Shop

I handed over payment, and the bagel shop guy said, “Um, I don’t know if we take these $2 bills….”

The customer behind me laughed, and said just what I was thinking: “You have to take ’em, man — they’re legal tender!”

Why do I get $2 bills from the bank at every opportunity? Because I live for moments like this, that’s why!

[Image found here.]

A Faceted Truncated Icosahedron With 602 Faces

In the first image of this faceted polyhedron shown, above, the faces are colored by face type. In the second image, the faces are colored by number of sides. The red faces are triangles, the yellow faces are quadrilaterals, and the blue faces are {10/4} polygons.

The third image, below, shows this faceted polyhedron in “rainbow colored mode.” I made these images using Stella 4d, which you can try for free at this website.

A Vertex-Based Zonish Snub Dodecahedron

This polyhedron has 4292 faces. In the first image shown, they are colored by face type. In the second, the coloring is done by the number of sides of each face.

Finally, the last image here shows this zonish polyhedron in “rainbow color mode.” All of these images were made using Stella 4d: Polyhedron Navigator, which you can try for free at http://www.software3d.com/Stella.php.