Given an integer **h** which is the side of an equilateral triangle formed by the same vertices as the Reuleaux triangle, the task is to find and print the area of the Reuleaux triangle.

**Examples:**

Input:h = 6

Output:25.3717

Input:h = 9

Output:57.0864

**Approach:** The shape made by the intersection of the three circles **ABC** is the **Reuleaux Triangle** and the triangle formed by the same vertices i.e. **ABC** is an equilateral triangle with side **h**.

Now, Area of sector ACB,

A1 = (π * h^{2}) / 6

Similarly, Area of sector CBA,A2 = (π * h^{2}) / 6

And, Area of sector BAC,A3 = (π * h^{2}) / 6

So,A1 + A2 + A3 = (π * h^{2}) / 2

Since, the area of the triangle is added thrice in the sum.

So, Area of the Reuleaux Triangle,A = (π * h^{2}) / 2 – 2 * (Area of equilateral triangle) = (π – √3) * h^{2}/ 2 = 0.70477 * h^{2}

Below is the implementation of the above approach:

## C++

`// C++ Program to find the area ` `// of Reuleaux triangle ` `#include <bits/stdc++.h> ` `using` `namespace` `std; ` ` ` `// Function to find the Area ` `// of the Reuleaux triangle ` `float` `ReuleauxArea(` `float` `a) ` `{ ` ` ` ` ` `// Side cannot be negative ` ` ` `if` `(a < 0) ` ` ` `return` `-1; ` ` ` ` ` `// Area of the Reuleaux triangle ` ` ` `float` `A = 0.70477 * ` `pow` `(a, 2); ` ` ` `return` `A; ` `} ` ` ` `// Driver code ` `int` `main() ` `{ ` ` ` `float` `a = 6; ` ` ` `cout << ReuleauxArea(a) << endl; ` ` ` `return` `0; ` `} ` |

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## Java

`// Java Program to find the area ` `// of Reuleaux triangle ` ` ` `public` `class` `GFG ` `{ ` ` ` `// Function to find the Area ` ` ` `// of the Reuleaux triangle ` ` ` `static` `double` `ReuleauxArea(` `float` `a) ` ` ` `{ ` ` ` ` ` `// Side cannot be negative ` ` ` `if` `(a < ` `0` `) ` ` ` `return` `-` `1` `; ` ` ` ` ` `// Area of the Reuleaux triangle ` ` ` `double` `A = (` `double` `)` `0.70477` `* Math.pow(a, ` `2` `); ` ` ` `return` `A; ` ` ` `} ` ` ` ` ` `// Driver code ` ` ` `public` `static` `void` `main(String args[]) ` ` ` `{ ` ` ` `float` `a = ` `6` `; ` ` ` `System.out.println(ReuleauxArea(a)) ; ` ` ` `} ` ` ` `// This code is contributed by Ryuga ` `} ` |

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## Python3

`# Python3 program to find the area ` `# of Reuleaux triangle ` `import` `math as mt ` ` ` `# function to the area of the ` `# Reuleaux triangle ` `def` `ReuleauxArea(a): ` ` ` ` ` `# Side cannot be negative ` ` ` `if` `a < ` `0` `: ` ` ` `return` `-` `1` ` ` `# Area of the Reauleax triangle ` ` ` `return` `0.70477` `*` `pow` `(a, ` `2` `) ` ` ` `# Driver code ` `a ` `=` `6` `print` `(ReuleauxArea(a)) ` ` ` `# This code is contributed ` `# by Mohit Kumar ` |

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## C#

`// C# Program to find the area ` `// of Reuleaux triangle ` ` ` `using` `System; ` ` ` `public` `class` `GFG ` `{ ` ` ` `// Function to find the Area ` ` ` `// of the Reuleaux triangle ` ` ` `static` `double` `ReuleauxArea(` `float` `a) ` ` ` `{ ` ` ` ` ` `// Side cannot be negative ` ` ` `if` `(a < 0) ` ` ` `return` `-1; ` ` ` ` ` `// Area of the Reuleaux triangle ` ` ` `double` `A = (` `double` `)0.70477 * Math.Pow(a, 2); ` ` ` `return` `A; ` ` ` `} ` ` ` ` ` `// Driver code ` ` ` `public` `static` `void` `Main() ` ` ` `{ ` ` ` `float` `a = 6; ` ` ` `Console.WriteLine(ReuleauxArea(a)) ; ` ` ` `} ` `} ` ` ` `// This code is contributed by Subhadeep ` |

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## PHP

`<?php ` `// PHP Program to find the area ` `// of Reuleaux triangle ` ` ` `// Function to find the Area ` `// of the Reuleaux triangle ` `function` `ReuleauxArea(` `$a` `) ` `{ ` ` ` ` ` `// Side cannot be negative ` ` ` `if` `(` `$a` `< 0) ` ` ` `return` `-1; ` ` ` ` ` `// Area of the Reuleaux triangle ` ` ` `$A` `= 0.70477 * pow(` `$a` `, 2); ` ` ` `return` `$A` `; ` `} ` ` ` `// Driver code ` `$a` `= 6; ` `echo` `ReuleauxArea(` `$a` `); ` ` ` `// This code is contributed ` `// by Akanksha Rai ` |

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**Output:**

25.3717

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