# Area of a square from diagonal length

Given an number d which is length of diagonal of a square, find its area. **Examples:**

Input : d = 10 Output : Area = 50 Input : d = 12.2 Output : Area = 74.42

Area of a square can be computed as (d * d)/2. Please see below image for details.

## C++

`// C++ Program to find the area of square` `// when its diagonal is given.` `#include <bits/stdc++.h>` `using` `namespace` `std;` `// Returns area of square from given` `// diagonal` `double` `findArea(` `double` `d)` `{` ` ` `return` `(d * d) / 2.0;` `}` `// Driver Code` `int` `main()` `{` ` ` `double` `d = 10;` ` ` `cout << (findArea(d));` ` ` `return` `0;` `}` `// This code is contributed by` `// Shivi_Aggarwal` |

## C

`// C Program to find the area of square` `// when its diagonal is given.` `#include <stdio.h>` `// Returns area of square from given` `// diagonal` `double` `findArea(` `double` `d)` `{` ` ` `return` `(d * d) / 2;` `}` `// Driver function.` `int` `main()` `{` ` ` `double` `d = 10;` ` ` `printf` `(` `"%.2f"` `, findArea(d));` ` ` `return` `0;` `}` |

## Java

`// Java Program to find the area of square` `// when its diagonal is given.` `class` `GFG` `{` ` ` `// Returns area of square from given` ` ` `// diagonal` ` ` `static` `double` `findArea(` `double` `d)` ` ` `{` ` ` `return` `(d * d) / ` `2` `;` ` ` `}` ` ` ` ` `// Driver code` ` ` `public` `static` `void` `main (String[] args)` ` ` `{` ` ` `double` `d = ` `10` `;` ` ` `System.out.println(findArea(d));` ` ` `}` `}` `// This code is contributed by Anant Agarwal.` |

## Python3

`# Python3 Program to find` `# the area of square` `# when its diagonal is given.` `# Returns area of square from given` `# diagonal` `def` `findArea(d):` ` ` `return` `(d ` `*` `d) ` `/` `2` `# Driver function.` `d ` `=` `10` `print` `(` `"%.2f"` `%` `findArea(d))` `# This code is contributed by` `# Smitha Dinesh Semwal` |

## C#

`// C# Program to find the area of square` `// when its diagonal is given.` `using` `System;` `class` `GFG` `{` ` ` `// Returns area of square from given` ` ` `// diagonal` ` ` `static` `double` `findArea(` `double` `d)` ` ` `{` ` ` `return` `(d * d) / 2;` ` ` `}` ` ` ` ` `// Driver code` ` ` `public` `static` `void` `Main ()` ` ` `{` ` ` `double` `d = 10;` ` ` `Console.WriteLine(findArea(d));` ` ` `}` `}` `// This code is contributed by vt_m.` |

## PHP

`<?php` `// PHP Program to find the area of` `// square when its diagonal is given.` `// Returns area of square` `// from given diagonal` `function` `findArea( ` `$d` `)` `{` ` ` `return` `(` `$d` `* ` `$d` `) / 2;` `}` ` ` `// Driver Code` ` ` `$d` `= 10;` ` ` `echo` `( findArea(` `$d` `));` ` ` `// This code is contributed by vt_m.` `?>` |

## Javascript

`<script>` `// JavaScript Program to find the area of square` `// when its diagonal is given.` ` ` `// Returns area of square from given` ` ` `// diagonal` ` ` `function` `findArea(d)` ` ` `{` ` ` `return` `(d * d) / 2;` ` ` `}` ` ` `// Driver code` ` ` `let d = 10;` ` ` `document.write(findArea(d));` ` ` `</script>` |

**Output:**

50.00