# 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)

My Personal Notes arrow_drop_up