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Sum of internal angles of a Polygon
  • Last Updated : 04 Nov, 2019

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 = 3
Output: 180
3-sided polygon is a triangle and the sum
of the interior angles of a triangle is 180.

Input: N = 6
Output: 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));
?>
Output:
540

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