The constructible regular 12-sided Polygon with Schläfli Symbol . The
Inradius , Circumradius , and Area can be computed directly from the formulas for a general
regular Polygon with side length and sides,
A Plane Perpendicular to a axis of a Dodecahedron or Icosahedron cuts the solid in a regular Decagonal Cross-Section (Holden 1991, pp. 24-25).
The Greek, Latin, and Maltese Crosses are all irregular dodecagons.
See also Decagon, Dodecagram, Dodecahedron, Greek Cross, Latin Cross, Maltese Cross, Trigonometry Values Pi/12, Undecagon
Holden, A. Shapes, Space, and Symmetry. New York: Dover, 1991.