# Largest sphere that can be inscribed inside a cube

Given here is a cube of side length a, the task is to find the biggest sphere that can be inscribed within it.

Examples:

```Input: a = 4
Output: 2

Input: a = 5
Output: 2.5
``` Approach:

From the 2d diagram it is clear that, 2r = a,
where, a = side of the cube
r = radius of the sphere
so r = a/2.

Below is the implementation of the above approach:

## C++

 `// C++ Program to find the biggest sphere ` `// inscribed within a cube ` `#include ` `using` `namespace` `std; ` ` `  `// Function to find the radius of the sphere ` `float` `sphere(``float` `a) ` `{ ` ` `  `    ``// side cannot be negative ` `    ``if` `(a < 0) ` `        ``return` `-1; ` ` `  `    ``// radius of the sphere ` `    ``float` `r = a / 2; ` ` `  `    ``return` `r; ` `} ` ` `  `// Driver code ` `int` `main() ` `{ ` `    ``float` `a = 5; ` `    ``cout << sphere(a) << endl; ` ` `  `    ``return` `0; ` `} `

## Java

 `// Java Program to find the biggest sphere ` `// inscribed within a cube ` ` `  `class` `GFG{ ` `// Function to find the radius of the sphere ` `static` `float` `sphere(``float` `a) ` `{ ` ` `  `    ``// side cannot be negative ` `    ``if` `(a < ``0``) ` `        ``return` `-``1``; ` ` `  `    ``// radius of the sphere ` `    ``float` `r = a / ``2``; ` ` `  `    ``return` `r; ` `} ` ` `  `// Driver code ` `public` `static` `void` `main(String[] args) ` `{ ` `    ``float` `a = ``5``; ` `    ``System.out.println(sphere(a)); ` ` `  `} ` `} ` `// This code is contributed by mits `

## Python3

 `# Python 3 Program to find the biggest  ` `# sphere inscribed within a cube ` ` `  `# Function to find the radius  ` `# of the sphere ` `def` `sphere(a): ` `     `  `    ``# side cannot be negative ` `    ``if` `(a < ``0``): ` `        ``return` `-``1` ` `  `    ``# radius of the sphere ` `    ``r ``=` `a ``/` `2` ` `  `    ``return` `r ` ` `  `# Driver code ` `if` `__name__ ``=``=` `'__main__'``: ` `    ``a ``=` `5` `    ``print``(sphere(a)) ` ` `  `# This code is contributed  ` `# by SURENDRA_GANGWAR `

## C#

 `// C# Program to find the biggest  ` `// sphere inscribed within a cube  ` `using` `System; ` ` `  `class` `GFG ` `{ ` `// Function to find the radius  ` `// of the sphere  ` `static` `float` `sphere(``float` `a)  ` `{  ` ` `  `    ``// side cannot be negative  ` `    ``if` `(a < 0)  ` `        ``return` `-1;  ` ` `  `    ``// radius of the sphere  ` `    ``float` `r = a / 2;  ` ` `  `    ``return` `r;  ` `}  ` ` `  `// Driver code  ` `static` `public` `void` `Main () ` `{ ` `    ``float` `a = 5;  ` `    ``Console.WriteLine(sphere(a));  ` `}  ` `}  ` ` `  `// This code is contributed by ajit  `

## PHP

 ` `

Output:

```2.5
```

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