Adjust the undecagon below by dragging the orange dot on any
By clicking on the top left command line, you can switch it between a
Some say that the word undecagon is incorrect because it is derived from Latin (una - "one") whereas
most polygon names are Greek in origin.
By that rule it would be called a hendecagon instead.
To avoid confusion simply call it an 11-gon.
Properties of regular undecagons
Like any regular polygon, to find the interior angle we use the formula
(180n–360)/n . For a undecagon, n=11.
See Interior Angles of a Polygon
To find the exterior angle of a regular undecagon, we use the fact that the exterior angle
with the interior angle, so in general it is given by the formula
See Exterior Angles of a Polygon
The Canadian dollar coin and the US Susan B Anthony dollar are undecagonal in shape. While the US dollar is actually round,
it appears to have 11 sides because of the undecagon inscribed just inside the rim, as seen below.