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A Regular Polygon with 108 sides: Area, Perimeter, Interior and Exterior Angles, Inradius, Circumradius



A regular polygon with 108 sides where the length of each side is 8 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 108 sides. What are the interior angles and exterior angles? 
If the length of each side is 8 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 108

Perimeter of a polygon with 108 sides = (side length) x 108 = 864 units

Area of a polygon with 108 sides = (n x Sidecot (Π/n))/4 = (n x 8cot (Π/108))/4 = 59387.5 square units

Sum of the interior angles of a polygon with 108 sides = 
 (n-2) x 180 degrees =  (108-2) x 180 degrees = 19080 degrees

Interior Angle of a polygon with 108 sides = (n-2) x 180/n degrees = (108-2) x 180/108 degrees = 176.66 degrees 

Exterior angle of a polygon with 108 sides = 180 - Interior Angle = 180 - 176.66 = 3.33 degrees

Inradius = Radius of In-circle = (side length) x cot (Π/108) = 8 x cot 1 = 274.94 units

Circumradius = Radius of Circum-circle = (side length) x cosec (Π/108) = 8 x cosec 1 degrees = 275.05 units

Symmetry Group = D108  108 rotational symmetries and 108 reflection symmetries. The "D" stands for di-hedral. 




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