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A regular Octadecagon where the length of each side is 2 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 2 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 36 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 2cot (Π/18))/4 = 102.08 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 2 x cot 10 = 11.34 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 2 x cosec 10 degrees = 11.51 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 3 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 3 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 54 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 3cot (Π/18))/4 = 229.68 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 3 x cot 10 = 17.01 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 3 x cosec 10 degrees = 17.27 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 4 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 4 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 72 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 4cot (Π/18))/4 = 408.33 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 4 x cot 10 = 22.68 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 4 x cosec 10 degrees = 23.03 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 5 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 5 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 90 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 5cot (Π/18))/4 = 638.01 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 5 x cot 10 = 28.35 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 5 x cosec 10 degrees = 28.79 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 6 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 6 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 108 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 6cot (Π/18))/4 = 918.74 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 6 x cot 10 = 34.02 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 6 x cosec 10 degrees = 34.55 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 7 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 7 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 126 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 7cot (Π/18))/4 = 1250.51 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 7 x cot 10 = 39.69 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 7 x cosec 10 degrees = 40.31 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon 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 18 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 = 18

Perimeter of a Octadecagon = side x 18 = 144 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 8cot (Π/18))/4 = 1633.32 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 8 x cot 10 = 45.37 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 8 x cosec 10 degrees = 46.07 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 9 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 9 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 162 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 9cot (Π/18))/4 = 2067.18 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 9 x cot 10 = 51.04 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 9 x cosec 10 degrees = 51.82 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 10 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 10 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 180 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 10cot (Π/18))/4 = 2552.07 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 10 x cot 10 = 56.71 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 10 x cosec 10 degrees = 57.58 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 11 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 11 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 198 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 11cot (Π/18))/4 = 3088.01 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 11 x cot 10 = 62.38 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 11 x cosec 10 degrees = 63.34 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 12 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 12 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 216 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 12cot (Π/18))/4 = 3674.99 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 12 x cot 10 = 68.05 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 12 x cosec 10 degrees = 69.1 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 13 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 13 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 234 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 13cot (Π/18))/4 = 4313 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 13 x cot 10 = 73.72 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 13 x cosec 10 degrees = 74.86 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 14 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 14 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 252 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 14cot (Π/18))/4 = 5002.07 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 14 x cot 10 = 79.39 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 14 x cosec 10 degrees = 80.62 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 15 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 15 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 270 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 15cot (Π/18))/4 = 5742.17 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 15 x cot 10 = 85.06 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 15 x cosec 10 degrees = 86.38 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 16 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 16 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 288 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 16cot (Π/18))/4 = 6533.31 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 16 x cot 10 = 90.74 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 16 x cosec 10 degrees = 92.14 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 17 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 17 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 306 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 17cot (Π/18))/4 = 7375.5 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 17 x cot 10 = 96.41 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 17 x cosec 10 degrees = 97.89 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 18 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 18 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 324 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 18cot (Π/18))/4 = 8268.72 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 18 x cot 10 = 102.08 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 18 x cosec 10 degrees = 103.65 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 19 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 19 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 342 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 19cot (Π/18))/4 = 9212.99 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 19 x cot 10 = 107.75 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 19 x cosec 10 degrees = 109.41 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 20 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 20 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 360 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 20cot (Π/18))/4 = 10208.3 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 20 x cot 10 = 113.42 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 20 x cosec 10 degrees = 115.17 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 21 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 21 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 378 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 21cot (Π/18))/4 = 11254.65 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 21 x cot 10 = 119.09 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 21 x cosec 10 degrees = 120.93 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 22 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 22 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 396 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 22cot (Π/18))/4 = 12352.05 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 22 x cot 10 = 124.76 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 22 x cosec 10 degrees = 126.69 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 23 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 23 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 414 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 23cot (Π/18))/4 = 13500.48 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 23 x cot 10 = 130.43 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 23 x cosec 10 degrees = 132.45 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 24 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 24 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 432 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 24cot (Π/18))/4 = 14699.96 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 24 x cot 10 = 136.11 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 24 x cosec 10 degrees = 138.21 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 25 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 25 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 450 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 25cot (Π/18))/4 = 15950.48 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 25 x cot 10 = 141.78 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 25 x cosec 10 degrees = 143.96 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 26 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 26 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 468 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 26cot (Π/18))/4 = 17252.03 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 26 x cot 10 = 147.45 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 26 x cosec 10 degrees = 149.72 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 27 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 27 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 486 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 27cot (Π/18))/4 = 18604.64 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 27 x cot 10 = 153.12 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 27 x cosec 10 degrees = 155.48 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 28 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 28 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 504 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 28cot (Π/18))/4 = 20008.28 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 28 x cot 10 = 158.79 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 28 x cosec 10 degrees = 161.24 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 29 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 29 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 522 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 29cot (Π/18))/4 = 21462.96 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 29 x cot 10 = 164.46 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 29 x cosec 10 degrees = 167 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral. 




A regular Octadecagon where the length of each side is 30 units. The units may either be inches or cm or km or miles: any unit of length.

You are given a Regular Polygon with 18 sides. What are the interior angles and exterior angles? 
If the length of each side is 30 units, what is the perimeter, area, circum-radius and in-radius of the polygon?

n = 18

Perimeter of a Octadecagon = side x 18 = 540 units

Area of a Octadecagon = (n x Sidecot (Π/n))/4 = (n x 30cot (Π/18))/4 = 22968.69 square units

Sum of the interior angles of a Octadecagon = 
 (n-2) x 180 degrees =  (18-2) x 180 degrees = 2880 degrees

Interior Angle of a Octadecagon = (n-2) x 180/n degrees = (18-2) x 180/18 degrees = 160 degrees 

Exterior angle of a Octadecagon = 180 - Interior Angle = 180 - 160 = 20 degrees

Inradius = Radius of In-circle = side x cot (Π/18) = 30 x cot 10 = 170.13 units

Circumradius = Radius of Circum-circle = side x cosec (Π/18) = 30 x cosec 10 degrees = 172.76 units

Symmetry Group = D18  18 rotational symmetries and 18 reflection symmetries. The "D" stands for di-hedral.