Given here is an equilateral triangle with side length a, the task is to find the area of the circle inscribed in that equilateral triangle.

**Examples:**

Input :a = 4Output :4.1887902047863905Input :a = 10Output :26.1799387799

**Approach:**

Area of equilateral triangle =

Semi perimeter of equilateral triangle =(a + a + a) / 2

Radius of inscribed circle r = Area of equilateral triangle / Semi perimeter of equilateral triangle

=

=Area of circle = PI*(r*r) =

Below is the implementation of above approach:

## C++

`// C++ program to find the area ` `// of circle which is inscribed ` `// in equilateral triangle ` `# include<bits/stdc++.h> ` `# define PI 3.14 ` `using` `namespace` `std; ` ` ` `// Function return the area of circle ` `// inscribed in equilateral triangle ` `float` `circle_inscribed(` `int` `a) ` `{ ` ` ` `return` `PI * (a * a) / 12; ` `} ` ` ` `// Driver code ` `int` `main() ` `{ ` ` ` `int` `a = 4; ` ` ` ` ` `cout << circle_inscribed(a); ` ` ` `return` `0; ` `} ` ` ` `// This code is contributed ` `// by Mahadev99 ` |

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## Java

`// Java program to find the area ` `// of circle which is inscribed ` `// in equilateral triangle ` `import` `java.io.*; ` ` ` `class` `GFG ` `{ ` ` ` `static` `double` `PI = ` `3.14` `; ` ` ` `// Function return the area of circle ` `// inscribed in equilateral triangle ` `static` `double` `circle_inscribed(` `int` `a) ` `{ ` ` ` `return` `PI * (a * a) / ` `12` `; ` `} ` ` ` `// Driver code ` `public` `static` `void` `main (String[] args) ` `{ ` ` ` `int` `a = ` `4` `; ` ` ` ` ` `System.out.println(circle_inscribed(a)); ` `} ` `} ` ` ` `// This code is contributed by anuj_67 ` |

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## Python3

`# Python3 program to find the area of circle ` `# which is inscribed in equilateral triangle ` ` ` `# import math library for pi value ` `from` `math ` `import` `pi ` ` ` `# Function return the area of circle ` `# inscribed in equilateral triangle ` `def` `circle_inscribed(a): ` ` ` `return` `pi` `*` `(a ` `*` `a) ` `/` `12` ` ` `# Driver code ` `a ` `=` `4` `print` `(circle_inscribed(a)) ` |

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## C#

`// C# program to find the area ` `// of circle which is inscribed ` `// in equilateral triangle ` `using` `System; ` ` ` `class` `GFG ` `{ ` `static` `double` `PI = 3.14; ` ` ` `// Function return the area of circle ` `// inscribed in equilateral triangle ` `static` `double` `circle_inscribed(` `int` `a) ` `{ ` ` ` `return` `PI * (a * a) / 12; ` `} ` ` ` `// Driver code ` `public` `static` `void` `Main () ` `{ ` ` ` `int` `a = 4; ` ` ` ` ` `Console.WriteLine( circle_inscribed(a)); ` `} ` `} ` ` ` `// This code is contributed ` `// by inder_verma ` |

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## PHP

`<?php ` `// PHP program to find the area ` `// of circle which is inscribed ` `// in equilateral triangle ` ` ` `// Function return the area of circle ` `// inscribed in equilateral triangle ` `function` `circle_inscribed(` `$a` `) ` `{ ` ` ` `return` `3.14 * (` `$a` `* ` `$a` `) / 12; ` `} ` ` ` `// Driver code ` `$a` `= 4; ` ` ` `echo` `circle_inscribed(` `$a` `); ` ` ` `// This code is contributed ` `// by Akanksha Rai(Abby_akku) ` |

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**Output:**

4.1887902047863905

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