#include<iostream>
#include<cstring>
#include<vector>
#include<cmath>
#include<iomanip>
using namespace std;
using LL = long long;
const double PI = acos(-1);
double v, R, d;

double f(double x){
    double sinx = sin(x);
    return 1 / v / (sqrt(sinx * sinx + 3) - sinx);
}

const double eps = 1e-12;

double simpson(double l, double r){
    double mid = (l + r) / 2;
    return (r - l) * (f(l) + 4 * f(mid) + f(r)) / 6;
}

double asr(double l, double r, double s){
    auto mid = (l + r) / 2;
    auto left = simpson(l, mid), right = simpson(mid, r);
    if (fabs(left + right - s) < eps) return left + right;
    return asr(l, mid, left) + asr(mid, r, right);
}

int main(){

#ifdef LOCAL
    freopen("data.in", "r", stdin);
    freopen("data.out", "w", stdout);
#endif

    cin.tie(0);
    cout.tie(0);
    ios::sync_with_stdio(0);
    cout << fixed << setprecision(20);

    int T;
    cin >> T;
    while(T--){
        cin >> v >> R >> d;

        auto check = [&](double mid){
            double l = d - v * mid;
            if (l + eps < 4 * R) return false;
            double a = PI - acos(2 * R / (l - 2 * R));
            double ans = asr(0, a, simpson(0, a)) * 2 * R;
            double dist = sqrt((l - 2 * R) * (l - 2 * R) - 4 * R * R);
            ans += dist * f(a);
            return ans <= mid;
        };

        double l = 0, r = (d - 4 * R) / v;
        for(int i = 0; i < 100; i++){
            double mid = (l + r) / 2;
            if (check(mid)) r = mid;
            else l = mid;
        }
        
        double ans = d / v;
        if (l <= r + eps && check(r)) ans = min(ans, r);
        cout << ans << '\n';
    }

}