Author: peterkagey

  • Straightedge and Compass Constructions (1 of 2)

    How many distinct constructions can be made with a straightedge and compass if we draw \(n\) lines and circles? Describing a straightedge-and-compass construction Initially we start with two points, which we call \((0,0)\) and \((1,0)\). At each step, we can do one of two things: We get new points whenever lines intersect with lines, lines…

  • Torus tilings

    Ever since Bill Keehn and I started writing our paper, “Counting Tilings of the 𝑛 × 𝑚 Grid, Cylinder, and Torus,” I’ve been noticing and taking photos of tiles that I see that exhibit interesting symmetries. My wife will sometimes kid on the square: “Whenever you take your phone out to take a picture of…

  • Fibonachos

    A few weeks ago I was going through my saved tweets, and I saw this one from Math Lady Hazel which reminded me of a story from early 2017 that I played a small part in. In January 2017, reddit user Teblefer asked the following question: Two people are sharing a plate of nachos. They…

  • Hexagons in Triangles

    At the beginning of April, I posted two animations related to hexagons inscribed inside of an equilateral triangle. Here I discuss a bit about the origin of these animations and give code so that you can reproduce these on your own. Gathering 4 Gardner gift exchange I first stumbled across this idea at the beginning…

  • G4G15 gift exchange: Parity Triangles from the OEIS

    In February 2024, I attended the Gathering 4 Gardner in Atlanta (G4G15), which has a tradition of a gift exchange, where you bring 170 copies of a small gift, and in turn you get a small gift from all of the exchange participants. One of these gifts, a set of 3D-printed fractals from Hideki Tsuiki…

  • Yan Zhang on power and Conway

    You know that feeling when someone expresses a feeling that you have better than you ever could figure out how to articulate it? While archiving my old liked tweets, I noticed that Yan Zhang had done it. Twice. I wanted to make sure that I copied these notes down so that I could still reference…

  • LEGO Truchet

    LEGO Truchet

    In the process of going through my old saved tweets as I transition away from Twitter, I saw this tweet from Dave Richeson who is now posts on Bluesky as @divbyzero.bsky.social. About one year after this, I made a LEGO Truchet tiling for Dave, not realizing that I had probably been unconsciously inspired by his!…

  • “A beautiful little problem!”

    “A beautiful little problem!”

    I’ve been going through my old Twitter saves, when I came across this one which was no longer available, but which intrigued me! The post is now gone from Twitter, but I found it via the WaybackMachine. Prove that if all the coefficients of the quadratic equation \[ax^2 + bx + c = 0\] are…

  • Hinged stellated dodecahedron

    Hinged stellated dodecahedron

    One of the earliest laser cutting projects I ever considered was when I was a graduate student: making a stellated dodecahedron. When I got to Harvey Mudd College and had the opportunity to use the laser cutter in the Makerspace for the first time, it was one of the first things I attempted. My initial…

  • JMM Exhibition of Mathematical Art

    JMM Exhibition of Mathematical Art

    I was going through some old saved tweets during my move to Bluesky, and my favorite tweets to come across were those that mean something different to me know than they did when I saved them. In particular, this tweet from 2021 shows that 2021 JMM Exhibition of Mathematical Art catalog, and little did I…