Triskaidecagon (13 sides)

Outer radius r_o
Outer radius r_o
Number of sides 13
Side length a_13=r_o*2*sqrt((5-sqrt(5))/2)
Area A=13/4*a*a/tan(pi/13)
sum of sides 13*a_13
Outer angle 360/13
Radius of inner circle r_i=a/(2*tan(36))
Diagonal d=sqrt((a_13/2)^2+h^2)
Height h = r_o  + r_i
Sum of angles 1980
Attention: Formulas are not correct yet. Website under construction.



 



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