# Program to find area of a circle

Last Updated : 20 Mar, 2024

Given the radius of a circle, find the area of that circle.

The area of a circle can simply be evaluated using the following formula.
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[Tex]Area = \pi r^2[/Tex]

where r is radius of circle and it maybe in float because value of pie is 3.14Â

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Approach: Using the given radius, find the area using the above formula: (pi * r * r) and print the result in float.
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C++ // C++ program to find area // of circle #include <iostream> const double pi = 3.14159265358979323846; using namespace std; // function to calculate the area of circle float findArea(float r) { return (pi * r * r); } // driver code int main() { float r, Area; r = 5; // function calling Area = findArea(r); // displaying the area cout << "Area of Circle is :" << Area; return 0; }  C // C program to find area // of circle #include <stdio.h> #include <math.h> #define PI 3.142 double findArea(int r) { return PI * pow(r, 2); } int main() { printf("Area is %f", findArea(5)); return 0; }  Java // Java program to find area // of circle class Test { static final double PI = Math.PI; static double findArea(int r) { return PI * Math.pow(r, 2); } // Driver method public static void main(String[] args) { System.out.println("Area is " + findArea(5)); } }  Python3 # Python3 program to find Area of a circle def findArea(r): PI = 3.142 return PI * (r*r); # Driver method print("Area is %.6f" % findArea(5)); # This code is contributed by Chinmoy Lenka  C# // C# program to find area of circle using System; class GFG { static double PI = Math.PI; static double findArea(int r) { return PI * Math.Pow(r, 2); } // Driver method static void Main() { Console.Write("Area is " + findArea(5)); } } // This code is contributed by Sam007.  PHP <?php // PHP program to find area // of circle function findArea( $r) {$PI =3.142; return $PI * pow($r, 2); } // Driver Code echo("Area is "); echo(findArea(5)); return 0; // This code is contributed by vt_m. ?>  Javascript <script> // Javascript program to find area // of circle let pi = 3.14159265358979323846; // function to calculate the area of circle function findArea(r) { return (pi * r * r); } // Driver code let r, Area; r = 5; // function calling Area = findArea(r); // displaying the area document.write("Area of Circle is :" + Area); // This code is contributed by Mayank Tyagi </script> 

Output

Area of Circle is :78.5398

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