Posted by: Dave Richeson | April 7, 2016

A Trig-free Proof of Crockett Johnson’s Theorem

I recently wrote a post about Crockett Johnson’s neusis construction of a regular heptagon. Johnson’s proof that the construction was correct required heavy trigonometry. I asked if there was a geometric proof that didn’t use trigonometry.

My friend Dan Lawson came to the rescue—he posted the following lovely proof on Twitter. Thanks Dan!

LawsonProof


Responses

  1. […] Dan Lawson has proved the theorem without trigonometry. Thanks, […]


Categories

%d bloggers like this: