func_code_string: #include <bits/stdc++.h>   using namespace std;   void lemon() {     double R1, R2;     int k;     scanf( %lf%lf%d , &R1, &R2, &k);     k++;     double xl = 1 / (R1 * 2), xr = 1 / (R2 * 2);     double xc = (xl + xr) / 2, rad = abs(xc - xl);     double yc = rad * (k - 1) * 2;     double len = sqrt(xc * xc + yc * yc);     double final = (1 / (len - rad) - 1 / (len + rad)) / 2;     printf( %.16lf n , final);   }   int main() {     ios::sync_with_stdio(true);     int tcase;     scanf( %d , &tcase);     while (tcase--) lemon();     return 0;   }   