# Program to calculate area of Enneagon

Enneagon is a polygon with 9 sides and 9 internal angles. Enneagon is also known as Nonagon. A regular nonagon has an internal angle of 140 degrees each. Sum of interior angles of the nonagon is 1260 degree.

The center of the circumcircle is also taken as the center of the regular Nonagon.

The line segment drawn the perpendicular to a side of the Nonagon is called the Apothem and is represented by ‘a’.

Area ≈ 6.1818 * s * s where s is side length.

Examples:

Input : 6 Output :Area of Regular Nonagon = 222.5448 Input : 8 Output :Area of Regular Nonagon = 395.6352

## C++

`// CPP program to find area of a Enneagon ` `#include <iomanip> ` `#include <iostream> ` `#include <math.h> ` `using` `namespace` `std; ` ` ` `// Function to calculate area of nonagon ` `double` `Nonagon_Area(` `double` `s) { ` ` ` `return` `(6.1818 * s * s); ` `} ` ` ` `// driver function ` `int` `main() { ` ` ` `double` `s = 6; ` `// Length of a side ` ` ` `cout << ` `"Area of Regular Nonagon = "` `<< std::setprecision(7) ` ` ` `<< Nonagon_Area(s); ` ` ` `return` `0; ` `} ` |

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## Java

`// Java program to find area of a Enneagon ` `class` `Nonagon { ` ` ` ` ` `// Function for calculating the area of the nonagon ` ` ` `public` `static` `double` `Nonagon_Area(` `double` `s) { ` ` ` `return` `((` `6.1818` `* (s * s))); ` ` ` `} ` ` ` ` ` `// driver code ` ` ` `public` `static` `void` `main(String[] args) { ` ` ` `double` `s = ` `6` `; ` `// Length of a side ` ` ` `System.out.print(` `"Area of Regular Nonagon = "` `+ Nonagon_Area(s)); ` ` ` `} ` `} ` |

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## Python

`# python program to find area of a Enneagon ` `length ` `=` `6` `Nonagon_area ` `=` `6.1818` `*` `(length ` `*` `*` `2` `) ` `print` `(` `"Area of regular Nonagon is = "` `, Nonagon_area) ` |

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## C#

`// C# program to find area of a Hexagon ` `using` `System; ` ` ` `class` `Nonagon { ` ` ` ` ` `// Function for calculating ` ` ` `// the area of the nonagon ` ` ` `public` `static` `double` `Nonagon_Area(` `double` `s) ` ` ` `{ ` ` ` `return` `((6.1818 * (s * s))); ` ` ` `} ` ` ` ` ` `// driver code ` ` ` `public` `static` `void` `Main() ` ` ` `{ ` ` ` `// Length of a side ` ` ` `double` `s = 6; ` ` ` `Console.WriteLine(` `"Area of Regular Nonagon = "` `+ ` ` ` `Nonagon_Area(s)); ` ` ` `} ` `} ` ` ` `// This article is contributed by vt_m ` |

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## PHP

`<?php ` `// PHP program to find area of a Hexagon ` ` ` ` ` `// Function to calculate ` ` ` `// area of nonagon ` ` ` `function` `Nonagon_Area(` `$s` `) ` ` ` `{ ` ` ` `return` `(6.1818 * ` `$s` `* ` `$s` `); ` ` ` `} ` ` ` `// Driver Code ` ` ` `// Length of a side ` `$s` `= 6; ` ` ` `echo` `"Area of Regular Nonagon = "` ` ` `, Nonagon_Area(` `$s` `); ` ` ` `// This code is contributed by anuj_67. ` `?> ` |

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**Output:**

Area of Regular Nonagon = 222.5448

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