DODECAGON

, a regular polygon of 12 equal sides and angles.

If the side of a Dodecagon be 1, its area will be equal to 3 times the tang. of nearly; and, the areas of plane figures being as the squares of their sides, therefore 11.1961524 multiplied by the square of the side of any Dodecagon, will give its area. See my Mensuration, pa. 114, 2d ed.

To inscribe a Dodecagon in a given Circle. Carry the radius 6 times round the circumference, which will divide it into 6 equal parts, or will make a hexagon; then bisect each of those parts, which will divide the whole into 12 parts, for the Dodecagon. See also other methods of describing the same figure in my Mensur. pa. 26, &c. See Polygon.