Program to find area of a circle

Area of a circle can simply be evaluated using following formula.

Area = pi * r^{2}where r is radius of circle

## 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 is 78.550000

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