Help me in solving TETRA problem

help
,
1

My issue

how to find radius of sphere inscribed in a tetrahedron and tangent to all faces when edges are given

My code

import java.util.*;
import java.lang.*;
import java.io.*;

class Codechef
{
	public static void main (String[] args) throws java.lang.Exception
	{
		// your code goes here

	}
}

Problem Link: Sphere in a tetrahedron Practice Coding Problem