Program to find the Area of Pentagon

Given the side of a Pentagon, the task is to find the area of the Pentagon.
Examples:

Input : a = 5
Output: Area of Pentagon: 43.0119

Input : a = 10
Output: Area of Pentagon: 172.047745

A regular pentagon is a five sided geometric shape whose all sides and angles are equal. Its interior angles are of 108 degrees each and its exterior angles are 72 degrees each. The sum of interior angles of a pentagon is 540 degrees. 

Let a be the side of Pentagon, then the formula to find the area of Pentagon given by
Area = 

C++

// C++ program to find the area of Pentagon
#include<bits/stdc++.h>
using namespace std;

// Function to find area of pentagon
float findArea(float a)
{
    float area;

    // Formula to find area
    area = (sqrt(5 * (5 + 2 * (sqrt(5)))) * a * a) / 4;

    return area;
}

// Driver code
int main()
{
    float a = 5;

    // function calling
    cout << "Area of Pentagon: " << findArea(a);

    return 0;
}

Java

// Java program to find the area of Pentagon
import java.io.*;

class GFG {

    // Function to find area of pentagon
    static float findArea(float a)
    {
        float area;

        // Formula to find area
        area = (float)(Math.sqrt(5 * (5 + 2
                * (Math.sqrt(5)))) * a * a) / 4;

        return area;
    }

    // Driver code
    public static void main (String[] args)
    {
        float a = 5;

        System.out.println("Area of Pentagon: "
                               + findArea(a));
    }
}

Python3

# Python3 program to find
# the area of Pentagon

# Import Math module
# to use sqrt function
from math import sqrt

# Function to find
# area of pentagon

def findArea(a):

    # Formula to find area
    area = (sqrt(5 * (5 + 2 *
           (sqrt(5)))) * a * a) / 4
    return area


# Driver code
a = 5

# call function findArea()
# to calculate area of pentagon
# and print the calculated area
print("Area of Pentagon: ",
               findArea(a))

# This code is contributed
# by ihritik

C#

// C# program to find
// the area of Pentagon
using System;

class GFG
{

    // Function to find
    // area of pentagon
    static float findArea(float a)
    {
        float area;

        // Formula to find area
        area = (float)(Math.Sqrt(5 * (5 + 2 *
                      (Math.Sqrt(5)))) *
                             a * a) / 4;

        return area;
    }

    // Driver code
    public static void Main ()
    {
        float a = 5;

        Console.WriteLine("Area of Pentagon: "+
                                  findArea(a));
    }
}

// This code is contributed
// by anuj_67.

PHP

<?php
// PHP program to find
// the area of Pentagon

// Function to find
// area of pentagon
function findArea($a)
{
    $area;

    // Formula to find area
    $area = (sqrt(5 * (5 + 2 *
            (sqrt(5)))) * $a *
                      $a) / 4;

    return $area;
}

// Driver code
$a = 5;

// function calling
echo "Area of Pentagon: " ,
              findArea($a);

// This code is contributed
// by anuj_67.
?>

Javascript

<script>

// Javascript program to find the area of Pentagon

// Function to find area of pentagon
function findArea(a)
{
    let area;

    // Formula to find area
    area = (Math.sqrt(5 * (5 + 2 * (Math.sqrt(5)))) * a * a) / 4;
    return area;
}

// Driver code
    let a = 5;

    // function calling
    document.write("Area of Pentagon: " + findArea(a));

// This code is contributed by Mayank Tyagi
</script>

Output:

Area of Pentagon: 43.0119

Time complexity: O(1)

Auxiliary Space: O(1), since no extra space has been taken.