Hendecagon
Polygon with eleven sides.
- A hendecagon is considered regular if all of its sides are the same length and if all of its interior angles have the same measure.
- If the hendecagon is regular, each of its interior angles measures about 147.3°.
Formula
The formula to calculate the area A of a regular hendecagon with side c is:
A =[latex]\frac{11{c}^{2}}{4}\textrm{cot(π/11)}[/latex].
Examples
Here is a regular hendecagon where the measure of an interior angle is expressed as a mixed number:
The Canadian one dollar coin is in the shape of a regular hendecagon.
Etymological Note
- This word comes from three Greek words: hens (one more), deca (ten) and gon (angle).
- Some authors use the term undecagon which comes from a Latin prefix (uno) and two Greek words.