Angle trisection - Wikipedia
Maths in a minute: Trisecting the angle
Measuring Angles Using Protractor – GeoGebra
The Basics – GeoGebra
The Tomahawk - an Angle Trisection Tool : 5 Steps (with Pictures) - Instructables
trisection of a segment – GeoGebra
What are construction marks in geometry? - Quora
What are construction marks in geometry? - Quora
Trisecting the Angle