#include <bits/stdc++.h>

#define long long long int
#define DEBUG
using namespace std;

// @author: pashka

struct test {
    double v, r, d;

    double f(double x) {
        return 2 * r / v / (sqrt(sin(x) * sin(x) + 3) - sin(x));
    }

    const int N = 10;

    double integrate_simple(double l, double r) {
        double res = 0;
        for (int i = 0; i <= N; i++) {
            double t = f(l + (r - l) * i / N);
            if (i == 0 || i == N) res += t;
            else if (i & 1) {
                res += 4 * t;
            } else {
                res += 2 * t;
            }
        }
        res *= (r - l) / N / 3;
        return res;
    }

    double integrate(double l, double r) {
        double m = (l + r) / 2;
        double s1 = integrate_simple(l, r);
        double s2 = integrate_simple(l, m) + integrate_simple(m, r);
        if (abs(s1 - s2) < 1e-9) {
            return s2;
        }
        return integrate(l, m) + integrate(m, r);
    }

    double calc(double a) {
        return integrate(0, a);
    }

    double time(double a) {
        double t = calc(a);
//        double x = 2 * r + t * v + 2 * r * sin(a - M_PI / 2);
//        double xx = x + 2 * r / sin(a - M_PI / 2);
//        double vv = v * (sqrt(sin(a) * sin(a) + 3) - sin(a));
//        double t2 = 2 * r / tan(a - M_PI / 2) / vv;

        double vv = v * (sqrt(sin(a) * sin(a) + 3) - sin(a));

        double vx = vv * sin(a) + v;
        double vy = -vv * cos(a);

        double x = 2 * r + t * v + 2 * r * sin(a - M_PI / 2);
        return t + (d - x) / vx;
    }

    double dist(double a) {
        double t = calc(a);
        double vv = v * (sqrt(sin(a) * sin(a) + 3) - sin(a));

        double vx = vv * sin(a) + v;
        double vy = -vv * cos(a);

//        cout << vx * vx + vy * vy << " " << 4 * v * v << "\n";

//        double xx = 2 * r + t * v + 2 * r * 2 * v / vy;
//        return xx;
        double x = 2 * r + t * v + 2 * r * sin(a - M_PI / 2);
        double y = 2 * r * cos(a - M_PI / 2);

        return x + y / vy * vx;
    }

    bool good(double a) {
        return dist(a) <= d;
    }

    void solve() {
        cin >> v >> r >> d;
        cout << setprecision(20);
        if (!good(M_PI)) {
            cout << d / v << "\n";
            return;
        }
        double l = M_PI / 2;
        double rr = M_PI;
        for (int i = 0; i < 100; i++) {
            double m = (l + rr) / 2;
            if (good(m)) {
                rr = m;
            } else {
                l = m;
            }
        }
        cout << time(l) << "\n";
    }
};

int main() {
    ios::sync_with_stdio(false);

    int n;
    cin >> n;
    for (int i = 0; i < n; i++) {
        test().solve();
    }

    return 0;
}