Biggest Reuleaux Triangle inscribed within a Square inscribed in an equilateral triangle

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++

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// 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;
}

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Java

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// 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

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Python3

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# 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

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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 [tabby title="PHP"]

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<?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

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Output:

3.79335


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