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Biggest Reuleaux Triangle inscribed within a Square inscribed in an equilateral triangle
  • Last Updated : 16 Mar, 2021

Given here is an equilateral triangle of sidelength a which inscribes a square which in turn inscribes a reuleaux triangle. The task is to find the maximum possible area of this reuleaux triangle.
Examples: 
 

Input : a = 5 
Output : 3.79335

Input : a = 9
Output : 12.2905

 

 

Approach: We know that the side of the square inscribed within an equilateral triangle of side length a   is, x = 0.464*a (Please refer here).
Also, in the reuleaux triangle, h = x.
So, Area of Reuleaux Triangle
 

A = 0.70477*h2 
  = 0.70477*(0.464*a)2

Below is the implementation of the above approach: 
 

C++




// C++ Program to find the biggest Reuleaux triangle
// inscribed within in a square which in turn
// is inscribed within an equilateral triangle
#include <bits/stdc++.h>
using namespace std;
 
// Function to find the biggest reuleaux triangle
float Area(float a)
{
 
    // side cannot be negative
    if (a < 0)
        return -1;
 
    // height of the reuleaux triangle
    float x = 0.464 * a;
 
    // area of the reuleaux triangle
    float A = 0.70477 * pow(x, 2);
 
    return A;
}
 
// Driver code
int main()
{
    float a = 5;
    cout << Area(a) << endl;
 
    return 0;
}

Java




// Java Program to find the biggest Reuleaux triangle
// inscribed within in a square which in turn
// is inscribed within an equilateral triangle
 
class GFG
{
     
// Function to find the biggest reuleaux triangle
static float Area(float a)
{
 
    // side cannot be negative
    if (a < 0)
        return -1;
 
    // height of the reuleaux triangle
    float x = 0.464f * a;
 
    // area of the reuleaux triangle
    float A = 0.70477f * (float)Math.pow(x, 2);
 
    return A;
}
 
// Driver code
public static void main (String[] args)
{
    float a = 5;
    System.out.println(String.format("%.5f", Area(a)));
}
}
 
// This code is contributed by chandan_jnu

Python3




# Python3 Program to find the biggest
# Reuleaux triangle inscribed within
# in a square which in turn is inscribed
# within an equilateral triangle
import math as mt
 
# Function to find the biggest
# reuleaux triangle
def Area(a):
 
    # side cannot be negative
    if (a < 0):
        return -1
 
    # height of the reuleaux triangle
    x = 0.464 * a
 
    # area of the reuleaux triangle
    A = 0.70477 * pow(x, 2)
 
    return A
 
# Driver code
a = 5
print(Area(a))
 
# This code is contributed by
# Mohit Kumar 29

C#




// C# Program to find the biggest Reuleaux
// triangle inscribed within in a square
// which in turn is inscribed within an
// equilateral triangle
using System;
 
class GFG
{
     
// Function to find the biggest
// reuleaux triangle
static float Area(float a)
{
 
    // side cannot be negative
    if (a < 0)
        return -1;
 
    // height of the reuleaux triangle
    float x = 0.464f * a;
 
    // area of the reuleaux triangle
    float A = 0.70477f * (float)Math.Pow(x, 2);
 
    return A;
}
 
// Driver code
public static void Main ()
{
    float a = 5;
    Console.WriteLine(String.Format("{0,0:#.00000}",
                                          Area(a)));
}
}
 
// This code is contributed by Akanksha Rai

PHP




<?php
// PHP Program to find the biggest Reuleaux
// triangle inscribed within in a square
// which in turn is inscribed within an
// equilateral triangle
 
// Function to find the biggest
// reuleaux triangle
function Area($a)
{
 
    // side cannot be negative
    if ($a < 0)
        return -1;
 
    // height of the reuleaux triangle
    $x = 0.464 * $a;
 
    // area of the reuleaux triangle
    $A = 0.70477 * pow($x, 2);
 
    return $A;
}
 
// Driver code
$a = 5;
echo Area($a) . "\n";
 
// This code is contributed
// by Akanksha Rai

Javascript




<script>
 
// Javascript Program to find the biggest Reuleaux triangle
// inscribed within in a square which in turn
// is inscribed within an equilateral triangle
 
// Function to find the biggest reuleaux triangle
function Area( a)
{
 
    // side cannot be negative
    if (a < 0)
        return -1;
 
    // height of the reuleaux triangle
    let x = 0.464 * a;
 
    // area of the reuleaux triangle
    let A = 0.70477 * Math.pow(x, 2);
 
    return A;
}
 
// Driver code
 
    let a = 5;
    document.write( Area(a).toFixed(5));
 
// This code contributed by Rajput-Ji
 
</script>
Output: 
3.79335

 

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