Few terms in the trig expression of the horizontal coords of vertex 6 of Sxx
dynamicsofpolygons.org
Originally - diagram was found in the paper [1].
----------
[1] The Edge Geometry of Regular Polygons -- Part 1 https://arxiv.org/abs/2103.06800
From pages 42-43 we can find a visual representation http://www.dynamicsofpolygons.org/LargeImages/N11DKH0Sxxpt2.... .
