# Area of circle which is inscribed in equilateral triangle

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) / 2Radius 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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