Nonagon
15-gon
21-gon
27-gon
33-gon
Visual geometry
What do the numbers 3,9,15,21,27,33,39,45,51,57,63,69,75,81,87,93,99... when it comes to regular polygons have in common?
A visual construction of a regular nonagon with compass and marked ruler (neusis construction of a nonagon).
Start with a hexagon and triangle as a base,