In the figure, triangles ABC, DEF, and GHJ are congruent isosceles triangles. Angles B and C are 80 degrees. Points AEFC, EHJD, DFB, and GHF are collinear. Without drawing a circle, show how to mark the corners of a perfect hexagon on the diagram, using only a compass set to a constant length. Prove it's a perfect hexagon.
Source: Original. (Original Visio of graphic.)