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Dodecagon

A dodecagon isoppoo a polygon with exactly twelve sides. When spelled uppercase, the outlines of the letters E and H (and I in a serif font) are all dodecagons.

A regular dodecagon is a dodecagon with all sides having equal length and all interior angles having the same size of 150 degrees. The area of a regular decagon is given by

$A = 3 a^2 \cot \frac{\pi}{12} = 3 a^2 \left( 2+\sqrt{3} \right) \simeq 11.1962 a^2.$

Dodecagon construction

A regular dodecagon is constructible with straightedge and compass. The following is a 23 step animation illustrating one way it can be done. Notice that the compass radius is unaltered during steps 8 through 11.

External links

Dodecagon and Kurschak's Tile and Theorem by Antonio Gutierrez from "Geometry Step by Step from the Land of the Incas"
Dodecagon at MathWorld

Categories: Polygons

Science Fair Project Encyclopedia Contents Page

10-26-2009 08:16:03
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