#include <bits/stdc++.h>
#define EPS 1e-9
using namespace std;

double v, r, d;

int sgn(double x) {
    if (x > EPS) return 1;
    if (x < -EPS) return -1;
    return 0;
}

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

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

double calc(double l, double r, double eps, double ans) {
    double mid = (l + r) / 2;
    double fl = simpson(l, mid), fr = simpson(mid, r);
    if (abs(fl + fr - ans) <= 15 * eps) return fl + fr + (fl + fr - ans) / 15;
    return calc(l, mid, eps / 2, fl) + calc(mid, r, eps / 2, fr);
}

void solve() {
    scanf("%lf%lf%lf", &v, &r, &d);

    double ans = d / v;
    const double PI = acos(-1);
    double head = PI / 2, tail = PI;
    while (tail - head > EPS) {
        double mid = (head + tail) / 2;
        double t = 2 * r / v * calc(0, mid, EPS, simpson(0, mid));
        double x = 2 * r * (1 - cos(mid)) + v * t;
        double y = 2 * r * sin(mid);
        double beta = atan2(y, d - x);
        double dot = (x - (2 * r + v * t)) * (2 * v * cos(beta) - v) - y * (2 * v * sin(beta));
        if (sgn(dot) >= 0) {
            tail = mid;
            ans = min(ans, t + sqrt((x - d) * (x - d) + y * y) / (2 * v));
        } else {
            head = mid;
        }
    }
    printf("%.9f\n", ans);
}

int main() {
    int tcase; scanf("%d", &tcase);
    while(tcase--) solve();
    return 0;
}