## Videos of my twist-hinged
dissection of an equilateral triangle to a square

In highlighting my article,
"Geometric Dissections Now Swing and Twist",
in the summer 2001 issue of the
*Mathematical Intelligencer,*
editor Chandler Davis regretted that the magazine
couldn't show movies of how the model of my
twist-hinged dissection of an equilateral triangle to a square swiveled.
But courtesy of the world wide web
and "cutting-edge video verité",
I am pleased to offer two short videos.
Note that the sizes of these are in MEGABYTES, not kilobytes,
so please don't try downloading them over a slow connection!
When in doubt, do the math to figure out how long the download
will take.

WARNING! These may not work on your computer!
When I produced them, I checked that they worked on
my workstation and also on a Windows machine in my department.
But I have since learned that they don't work on
a number of other machines.
I'm trying to find out why.
Stay tuned!

In the first video
(in avi format, with a playing time of 35 seconds),
I twist a nifty model of my twist-hinged dissection.
I start with an equilateral triangle, twist the pieces around
to produce a square, and then twist the model back to the triangle.
Warning: The size of the video file is 22.3 MEGABYTES.

In the second video
(in avi format, with a playing time of 1 minute),
I explain how I discovered the twist-hinged dissection.
It is based on a well-known swing-hinged dissection
to which I applied a certain conversion that I had discovered.
Warning: The size of the video file is 40.3 MEGABYTES.

My thanks to Ananth Grama for the use of his Sony laptop
and his help in creating these videos.
My thanks also to Wayne Daniel, who crafted the two models
out of peroba rosa wood.

*Last updated September 19, 2001.*