http://mathgardenblog.blogspot.co.uk/2013/10/basic-compass-straightedge-construction.html

http://upload.wikimedia.org/wikipedia/commons/8/85/Stereographic_projection_in_3D.png

http://www.princeton.edu/~hos/Mahoney/articles/mathnat/fig12.gif

http://stackoverflow.com/questions/25207608/splitting-polygon-in-2-equal-parts

http://www.uwgb.edu/dutchs/Graphics-Other/PSCI/trisect1.gif

http://home.earthlink.net/~serotonin/tridiag.GIF

http://jn.physiology.org/content/jn/102/5/3046/F5.large.jpg