DECAGONAL - 2 reference results
| Regular decagon | |||
|---|---|---|---|
| Edges and vertices | 10 | ||
| Schläfli symbols | {10} t{5} | ||
| Coxeter–Dynkin diagrams | >- | Symmetry group | Dihedral (D10) |
| Area (with t=edge length) | |||
| Internal angle (degrees) | 144° | ||
In geometry, a decagon is any polygon with ten sides and ten angles, and usually refers to a regular decagon, having all sides of equal length and all angles equal to 144°, therefore making each angle of a regular decagon be 144°. Its Schläfli symbol is {10}. The area of a regular decagon of side length a is given by
& simeq 7.694208843, a^2.end{align}
Construction
A regular decagon is constructible with a compass and straightedge.- Complete steps 1 though 6 of constructing a pentagon.
- Extend a line from each corner of the pentagon through the center of the circle made in step 1 of constructing a pentagon to the opposite side of that same circle.
- The five corners of the pentagon constitute every other corner of the decagon. The remaining five corners of the decagon are those points where the lines of step 2 cross the original circle (but not a pentagon corner).
See also
External links
- Definition and properties of a decagon With interactive animation
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Last updated on Sunday September 28, 2008 at 19:16:14 PDT (GMT -0700)
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This article is licensed under the GNU Free Documentation License.
Last updated on Sunday September 28, 2008 at 19:16:14 PDT (GMT -0700)
View this article at Wikipedia.org - Edit this article at Wikipedia.org - Donate to the Wikimedia Foundation
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