# Find the radius of the circles which are lined in a row, and distance between the centers of first and last circle is given

Given here are **n** circles which touch each other externally, and are lined up in a row. The distance between the centers of the first and last circle is given. The circles have a radius of equal length. The task is to find the radius of each circle. **Examples:**

Input:d = 42, n = 4Output:The radius of each circle is 7Input:d = 64, n = 5Output:The radius of each circle is 8

**Approach**:

Suppose there are **n** circles each having radius of length **r**.

Let, the distance between the first and last circles = **d**

From the figure, it is clear, **r + r + (n-2)*2r = d ****2r + 2nr – 4r = d ****2nr – 2r = d**

so, **r = d/(2n-2)**

## C++

`// C++ program to find radii of the circles` `// which are lined in a row` `// and distance between the` `// centers of first and last circle is given` `#include <bits/stdc++.h>` `using` `namespace` `std;` `void` `radius(` `int` `n, ` `int` `d)` `{` ` ` `cout << ` `"The radius of each circle is "` ` ` `<< d / (2 * n - 2) << endl;` `}` `// Driver code` `int` `main()` `{` ` ` `int` `d = 42, n = 4;` ` ` `radius(n, d);` ` ` `return` `0;` `}` |

## Java

`// Java program to find radii of the circles` `// which are lined in a row` `// and distance between the` `// centers of first and last circle is given` `import` `java.io.*;` `class` `GFG` `{` `static` `void` `radius(` `int` `n, ` `int` `d)` `{` ` ` `System.out.print( ` `"The radius of each circle is "` ` ` `+d / (` `2` `* n - ` `2` `));` `}` `// Driver code` `static` `public` `void` `main (String []args)` `{` ` ` `int` `d = ` `42` `, n = ` `4` `;` ` ` `radius(n, d);` `}` `}` `// This code is contributed by anuj_67..` |

## Python3

`# Python program to find radii of the circles` `# which are lined in a row` `# and distance between the` `# centers of first and last circle is given` `def` `radius(n, d):` ` ` `print` `(` `"The radius of each circle is "` `,` ` ` `d ` `/` `(` `2` `*` `n ` `-` `2` `));` `d ` `=` `42` `; n ` `=` `4` `;` `radius(n, d);` `# This code is contributed by PrinciRaj1992` |

## C#

`// C# program to find radii of the circles` `// which are lined in a row` `// and distance between the` `// centers of first and last circle is given` `using` `System;` `class` `GFG` `{` `static` `void` `radius(` `int` `n, ` `int` `d)` `{` ` ` `Console.Write( ` `"The radius of each circle is "` ` ` `+d / (2 * n - 2));` `}` `// Driver code` `static` `public` `void` `Main ()` `{` ` ` `int` `d = 42, n = 4;` ` ` `radius(n, d);` `}` `}` `// This code is contributed by anuj_67..` |

## Javascript

`<script>` `// javascript program to find radii of the circles` `// which are lined in a row` `// and distance between the` `// centers of first and last circle is given` `function` `radius(n , d)` `{` ` ` `document.write( ` `"The radius of each circle is "` ` ` `+d / (2 * n - 2));` `}` `// Driver code` `var` `d = 42, n = 4;` `radius(n, d);` `// This code is contributed by 29AjayKumar ` `</script>` |

**Output:**

The radius of each circle is 7

**Time Complexity: **O(1)

**Auxiliary Space:** O(1)