题目链接：http://acm.hdu.edu.cn/showproblem.php?pid=5733
题面：
tetrahedron
Time Limit: 2000/1000 MS (Java/Others) Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 399 Accepted Submission(s): 153
Problem Description Given four points ABCD, if ABCD is a tetrahedron, calculate the inscribed sphere of ABCD.
Input Multiple test cases (test cases ≤100 ).
Each test cases contains a line of 12 integers