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The relatively straightforward swing-hinged dissection of an equilateral triangle to a square in this video is called “Dudeney’s dissection” and has been known since 1902. For a gallery of hinged dissections, check out Tse-hsuan Yang’s page at Taiwan’s National Tsing Hua University.

Sean Michael Ragan

I am descended from 5,000 generations of tool-using primates. Also, I went to college and stuff. I write for MAKE, serve as Technical Editor for MAKE magazine, and develop original DIY content for Make: Projects.



  1. Simon says:

    Are those hinges a standard hardware item and if so what are they called?

    1. Adam says:

      I wish someone around here knew the answer to your question, Simon. I contacted Chris Sangwin, one of the authors of “How Round is Your Circle” and the guy who made that youtube video. He told me that John Bryant has the information about the hardware, but John does not have an email address. However, Chris mentioned that he thought John found those hinges in with standard cabinet hardware, but I have been searching for days and haven’t had much luck.

      So if anyone seeing this has any clue, please contact me or leave a comment on this video.

      1. Adam says:

        oops, I didn’t leave contact information and I don’t think I will. If anyone has any leads on this type of hinge, please just leave a comment here and I will be checking back periodically. Hopefully someone out there knows.

        also, John Bryant is another author of the book “How Round is Your Circle?” It’s a good read if you get the chance. There are some really neat potential for projects and explorations in there.

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