# Largest sphere that can be inscribed inside a cube

Last Updated : 11 Jul, 2022

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

 ``

## Javascript

 ``

Output:

`2.5`

Time Complexity: O(1)

Auxiliary Space: O(1)

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