Angle Trisection by Paper Folding!

Creation of this applet was inspired by a reference contained in Matt Parker's book, Things to Make and Do in the Fourth Dimension (pages 35 - 37). Credit for the discovery of this method of angle trisection via paper folding comes from Hisashi Abe (Hokkaido University, Japan, 1980). The goal here is to TRISECT the RED ANGLE. You can alter the size of the red angle by using the red slider. You can move the LARGE WHITE POINT as well.

Angle Trisection via Paper Folding: Can you do this with paper?


How can we formally prove why this method of angle trisection actually works?


What aspect(s) about this construction cause this red angle to be impossible to trisect via a pure "compass and straightedge" method?

Quick (Silent) Demo