# Sum of internal angles of a Polygon

Given an integer **N**, the task is to find the sum of interior angles of an **N-sided** polygon. A plane figure having a minimum of three sides and angles is called a polygon.**Examples:**

Input:N = 3Output:180

3-sided polygon is a triangle and the sum

of the interior angles of a triangle is 180.Input:N = 6Output:720

**Approach:** The sum of internal angles of a polygon with **N** sides is given by **(N – 2) * 180**

Below is the implementation of the above approach:

## C++

`// C++ implementation of the approach` `#include <bits/stdc++.h>` `using` `namespace` `std;` `// Function to return the sum of internal` `// angles of an n-sided polygon` `int` `sumOfInternalAngles(` `int` `n)` `{` ` ` `if` `(n < 3)` ` ` `return` `0;` ` ` `return` `(n - 2) * 180;` `}` `// Driver code` `int` `main()` `{` ` ` `int` `n = 5;` ` ` `cout << sumOfInternalAngles(n);` ` ` `return` `0;` `}` |

## Java

`// Java implementation of the approach` `class` `GFG {` ` ` `// Function to return the sum of internal` ` ` `// angles of an n-sided polygon` ` ` `static` `int` `sumOfInternalAngles(` `int` `n)` ` ` `{` ` ` `if` `(n < ` `3` `)` ` ` `return` `0` `;` ` ` `return` `((n - ` `2` `) * ` `180` `);` ` ` `}` ` ` `// Driver code` ` ` `public` `static` `void` `main(String args[])` ` ` `{` ` ` `int` `n = ` `5` `;` ` ` `System.out.print(sumOfInternalAngles(n));` ` ` `}` `}` |

## C#

`// C# implementation of the approach` `using` `System;` `class` `GFG {` ` ` `// Function to return the sum of internal` ` ` `// angles of an n-sided polygon` ` ` `static` `int` `sumOfInternalAngles(` `int` `n)` ` ` `{` ` ` `if` `(n < 3)` ` ` `return` `0;` ` ` `return` `((n - 2) * 180);` ` ` `}` ` ` `// Driver code` ` ` `public` `static` `void` `Main()` ` ` `{` ` ` `int` `n = 5;` ` ` `Console.Write(sumOfInternalAngles(n));` ` ` `}` `}` |

## Python

`# Python3 implementation of the approach` `# Function to return the sum of internal` `# angles of an n-sided polygon` `def` `sumOfInternalAngles(n):` ` ` `if` `(n < ` `3` `):` ` ` `return` `0` ` ` `return` `((n ` `-` `2` `) ` `*` `180` `)` `# Driver code` `n ` `=` `5` `print` `(sumOfInternalAngles(n))` |

## PHP

`<?php` `// PHP implementation of the approach` `// Function to return the sum of internal` `// angles of an n-sided polygon` `function` `sumOfInternalAngles(` `$n` `)` `{` ` ` `if` `(` `$n` `< 3)` ` ` `return` `0;` ` ` `return` `((` `$n` `- 2) * 180);` `}` `// Driver code` `$n` `= 5;` `echo` `(sumOfInternalAngles(` `$n` `));` `?>` |

## Javascript

`<script>` `// JavaScript implementation of the approach` `// Function to return the sum of internal` `// angles of an n-sided polygon` `function` `sumOfInternalAngles(n)` `{` ` ` `if` `(n < 3)` ` ` `return` `0;` ` ` `return` `(n - 2) * 180;` `}` `// Driver code` ` ` `let n = 5;` ` ` `document.write(sumOfInternalAngles(n));` `// This code is contributed by Mayank Tyagi` `</script>` |

**Output:**

540