Decagon
The constructible regular 10-sided Polygon with Schläfli Symbol 
. TheInradius 
, Circumradius 
, and Area can be computed directly from the formulas for a generalregular Polygon with side length 
and 
sides,
 |  |  | (1) |
 | |  | (2) |
 | |  | (3) |
Here,
is the Golden Mean.See also Decagram, Dodecagon, Trigonometry Values Pi/10, Undecagon
References
Dixon, R. Mathographics. New York: Dover, p. 18, 1991.
- Elliptic Integral of the Second Kind
- Elliptic Integral of the Third Kind
- Elliptic Integral Singular Value
- Elliptic Integral Singular Value k1
- Elliptic Integral Singular Value k2
- Elliptic Integral Singular Value k3
- Ellipticity
- Elliptic Lambda Function
- Elliptic Logarithm
- Elliptic Modular Function
- Elliptic Paraboloid
- Elliptic Partial Differential Equation
- Elliptic Plane
- Elliptic Point
- Elliptic Pseudoprime
- Elliptic Rotation
- Elliptic Theta Function
- Elliptic Torus
- Elliptic Umbilic Catastrophe
- Ellison-Mendès-France Constant
- Elongated Cupola
- Elongated Dipyramid
- Elongated Dodecahedron
- Elongated Gyrobicupola
- Elongated Gyrocupolarotunda