Hendecagon

File:Regular hendecagon.svg

A hendecagon

A hendecagon or undecagon or 11-gon is a shape with 11 sides and 11 corners.

Regular hendecagon

All sides of a regular hendecagon are the same length. Each corner is 147.27°. All corners added together equal 1619.97°.

Area

The amount of space a regular hendecagon takes up is

<math> \alpha = \frac{(n - 2)}{n} \cdot 180^\circ = \frac{9}{11} \cdot 180^\circ \approx 147{,}273^\circ</math>

<math>A = \frac{11}{4}a^2 \cot \frac{\pi}{11} \approx 9,36564a^2 \,</math>

a is the length of one of its sides.