The accepted name of a 12-sided polygon is "dodecagon." A polygon is a two-dimensional shape consisting of angles and straight lines in a closed system. The word "polygon" comes from the Greek "poly," which means "many" and "gon," which means "sides."
A dodecagon, like all polygons, is made up of of several parts:
- Straight line segments called sides.
- Several vertices, where the points of two sides meet. A dodecagon has 12 vertices.
- Diagonals, which are lines connecting two vertices, but are not sides.
- Interior angles formed inside by two adjacent sides.
- Exterior angles formed outside by adjacent sides.
The number of diagonals in a polygon can be calculated by the formula 1/2N(N-3), where N is the number of sides. In a dodecagon, the number of diagonals is equal to 1/2(12(12-3), or 54. The sum of all interior angles of a polygon can be calculated by subtracting 2 from the number of sides and multiplying by 180 degrees. The sum of a dodecagon is 1800 degrees.
Polygons that have equal sides and angles are called regular polygons. A regular dodecagon has angles that are 150 degrees each (1800/12). Equiangular polygons have angles that are equal nut not sides. Conversely, equilateral polygons have sides that are equal but not angles.