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 =

*** QuickLaTeX cannot compile formula: *** Error message: Error: Nothing to show, formula is emptySemi perimeter of equilateral triangle =

(a + a + a) / 2

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

=*** QuickLaTeX cannot compile formula: *** Error message: Error: Nothing to show, formula is empty=

*** QuickLaTeX cannot compile formula: *** Error message: Error: Nothing to show, formula is emptyArea of circle = PI*(r*r) =

*** QuickLaTeX cannot compile formula: *** Error message: Error: Nothing to show, formula is empty

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` |

## 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` |

## 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))` |

## 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` |

## 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)` |

## Javascript

`<script>` `// javascript program to find the area` `// of circle which is inscribed` `// in equilateral triangle` `let PI = 3.14;` `// Function return the area of circle` `// inscribed in equilateral triangle` `function` `circle_inscribed( a)` `{` ` ` `return` `PI * (a * a) / 12;` `}` `// Driver code` `let a = 4;` ` ` `document.write(circle_inscribed(a).toFixed(5));` `// This code contributed by gauravrajput1` `</script>` |

**Output:**

4.1887902047863905

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