A octadecagonA octadecagon or 18-gon is a shape with 18 sides and 18 corners.
Regular octadecagon
All sides of a regular octadecagon are the same length. Each corner is 160°. All corners added together equal 2880°.
Area
The amount of space a regular octadecagon takes up is
The area of a regular octadecagon of side length a is given by
![{\displaystyle A={\frac {18}{4))a^{2}\cot {\frac {\pi }{18))\simeq 25,5208a^{2))](https://wikimedia.org/api/rest_v1/media/math/render/svg/5180e02f59d782de61a890f5f928688ee26f3f37)
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Special cases, including regular polygons with their own names, in parentheses List of polygons by number of sides |
1–10 sides | | |
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11–20 sides | |
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21–30 sides | |
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31–50 sides | |
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51–100 sides (selected) | |
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>100 sides | |
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Star polygons (5–12 sides) | |
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Triangles | |
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Quadrilaterals | |
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