/*
     _/_/_/              _/                     _/_/_/                                               
  _/           _/_/_/                        _/         _/    _/    _/_/_/   _/_/_/       _/_/_/   
 _/         _/    _/   _/                   _/  _/_/   _/    _/  _/    _/   _/    _/   _/    _/    
_/         _/    _/   _/                   _/    _/   _/    _/  _/    _/   _/    _/   _/    _/     
 _/_/_/     _/_/_/   _/                     _/_/_/     _/_/_/    _/_/_/   _/    _/     _/_/_/      
                            _/_/_/_/_/                                                    _/       
                                                                                     _/_/_/
*/
#include <bits/stdc++.h>

using namespace std;

constexpr double pi = acos(-1.0l);
constexpr double eps = 1e-9;
#define hps eps*0.5
double a, b, v, r, d;

double f(double x) {
    return (double)2.0l * r / v / (sqrtl(3.0l + sinl(x) * sinl(x)) - sinl(x));
}

double simpson(double l,double r){
    return (r-l)*(f(l)+f(r)+4.0l*f((l+r)/2.0l))/6.0l;
}

double jf(double l,double r,double ans,double step){
    double mid=(1.0l*l+r)/2.0l;
    double fl=simpson(l,mid),fr=simpson(mid,r);
    if(abs(fl+fr-ans)<15.0l*eps&&step<0.0l)  return ans;
    else return jf(l,mid,fl,step-1.0l)+jf(mid,r,fr,step-1.0l);
}

void solve()
{
srand(998244353);
    cin >> v >> r >> d;
    // cout << v << ' ' << r << ' ' << d << '\n';
    double l = 1.0l*pi/2.0l, rr = pi;
    auto check = [&](double mid) {
        double t = jf((double)0.0l, mid, simpson(0.0l, mid), 0.0l);
        double dis = 2.0l * r + v * t;
        //cout<<mid<<'\n';
        //cout << dis << '\n';
        double delta = d - dis;
        double shengyu = pi - mid;
        //cout << delta << '\n';
        double dd = sqrt(delta * delta + 4 * r * r - 4 * r * delta * cos(shengyu));
        double s1 = 2 * r * sin(shengyu) / dd;
        double s2 = (sqrtl(3.0l + sinl(mid) * sinl(mid)) - sinl(mid)) * cos(mid) / -2 ;
        //cout<<shengyu<<" "<<s2<<"\n";
        if(s2 < s1) {
            return false;
        } return true;
    };
    for(int i = 1; i <= 50; i++) {
        double mid = (l + rr) / 2;
        if(check(mid)) {
            rr = mid;
        } else {
            l = mid;
        }
    }
    double t = jf((double)0.0l, rr, simpson(0, rr), 0);
    double shengyu = pi - rr;
    double dis = 2.0l * r + v * t;
    double delta = d - dis;
    double py = 2 *r*sin(shengyu);
    double px = 2 *r*cos(shengyu);
    double dd = sqrt(delta * delta + 4 * r * r - 4 * r * delta * cos(shengyu));
    // cout << t << '\n';
    double t2 = d / v,he = (d - 4 * r ) / v;
    cout << fixed << setprecision(10) << '\n';
    if(t+dd /2 / v > he)
    cout << t2 << '\n';
    else
    cout << t + dd / 2 / v<< '\n';
}

signed main() {

     ios::sync_with_stdio(false);
     cin.tie(nullptr);
     cout.tie(nullptr);
     int t;
     cin >> t;
     while(t--) {
          solve();
     }
     return 0;
}