A Tucker hexagon is a hexagon inscribed in a reference triangle that has sides which are alternately parallel and antiparallel to the
corresponding sides of the triangle. Tucker hexagons are always cyclic,
and the corresponding circumscribing circle is called a Tucker
circle.
Thomsen's figure is similar to a Tucker hexagon; Thomsen's hexagon closes after six parallels, while a Tucker hexagon closes after
alternately three parallels and three antiparallels.
