Octadecagon and 2{9/4} or two enneagrams, {18/6} is reduced to 6{3} or 6 equilateral triangles, and finally {18/9} is reduced to 9{2} as nine digons. Deeper truncations of the regular enneagon and enneagrams can produce isogonal (vertex-transitive) intermediate octadecagram forms with equally spaced vertices and two edge lengths. Other truncations form double coverings: t{9/8}={18/8}=2{9/4}, t{9/4}={18/4}=2{9/2}, t{9/2}={18/2}=2{9}. The regular octadecagon is the Petrie polygon for a number of higher-dimensional polytopes, shown in these skew orthogonal projections from Coxeter planes: Octadecagon An octadecagon (or octakaidecagon) or 18-gon is an eighteen-sided polygon. A "regular octadecagon" has a Schläfli symbol {18} and can be constructed
Hampton Sides Hampton Sides (Wade) Hampton Sides (born 1962) is an American historian, author and journalist. He is the author of "Americana," "Hellhound on His Trail," "Ghost Soldiers," "Blood and Thunder," and other bestselling works of narrative history and literary non-fiction. Sides is editor-at-large for "Outside" magazine and has written for such periodicals as "National Geographic", "The New Yorker", "Esquire", "Men's Journal", and "The Washington Post". His magazine work, collected in numerous published anthologies, has been twice nominated for National Magazine Awards for feature writing. A native of Memphis, Sides attended PDS Memphis and Memphis University School, and graduated from Yale with