Angle Trisection -- from Wolfram MathWorld

Angle trisection is the division of an arbitrary angle into three equal angles. It was one of the three geometric problems of antiquity for which solutions using only compass and straightedge were sought. The problem was algebraically proved impossible by Wantzel (1836). Although trisection is not possible for a general angle using a Greek construction, there are some specific angles, such as pi/2 and pi radians (90 degrees and 180 degrees, respectively), which can be trisected. Furthermore

Angle trisection - Wikipedia

Is it possible to draw a triquetra using the golden ratio? - Quora

Angle Trisection -- from Wolfram MathWorld

PDF) A Cool Method of Trisecting 45 Degree Angle

定規とコンパスを使った作図

Angle trisection - Wikipedia

Angle Trisection -- from Wolfram MathWorld

Bisection - Wikiwand

Pat'sBlog: Trisecting the General Angle, A Plethora of Pretty Approaches

Can a regular hendecagon be drawn with only a compass, straightedge, and angle quintisector? If so, why exactly? - Quora

Archimedes's Neusis Angle-Trisection - Wolfram Demonstrations Project

Angle Trisection -- from Wolfram MathWorld

Programming with triangles! - #16 by jremington - Programming Questions - Arduino Forum

Tomahawk Trisection of an Angle - Wolfram Demonstrations Project