#include<bits/stdc++.h>
using std::cin;
using std::cout;
using db = long double;
using cp = std::complex<db>;
db f(db t) {
	db s = std::sin(t);
	return std::sqrt(3 + s * s);
}
const int N = 1e6;
const db pi = std::acos(-1);
db beg[N + 1];
db sum[N + 1];
db guess(db l, db r) {
	return (f(l) + f(r) + f((l + r) / 2) * 4) / 6 * (r - l);
}
void init() {
	for(int i = 0;i <= N;++i) {
		beg[i] = pi / N * i;
	}
	for(int i = 0;i < N;++i) {
		sum[i + 1] = sum[i] + guess(beg[i], beg[i + 1]);
	}
}
db calc(db t) {
	int p = std::upper_bound(beg, beg + N, t) - beg - 1;
	db su = sum[p] + guess(beg[p], t);
	su += (1 - std::cos(t));
	return su / 3 * 2;
}

int main() {
	std::ios::sync_with_stdio(false), cin.tie(0);
	#ifdef zqj
	freopen("$.in", "r", stdin);
	#endif
	init();
	int T;
	cin >> T;
	for(int i = 0;i < T;++i) {
		db v, R, d, V;
		cin >> v >> R >> d;
		d /= R;
		v /= R;
		R /= R;
		V = v;
		auto gett = [&](db ang) { return calc(ang) / v; };
		db l = pi / 2 + 1e-8, r = pi - 1e-8;
		// cout << gett(pi) << '\n';
		// cout << gett(pi) * v + 3 * R << '\n';
		if(gett(r) * v + 3 * R <= d) {
			db ans = (d - R) / v;
			for(int i = 0;i < 100;++i) {
				db mid = (l + r) / 2;
				db T = gett(mid);
				cp o0 = cp(2, 0) + cp(v, 0) * T;
				cp o1 = o0 + db(2) * cp(std::cos(pi - mid), std::sin(pi - mid));
				cp v = cp(std::sin(mid), std::cos(mid)) * (f(mid) - std::sin(mid)) + cp(R, 0);
				// cout << abs(v) << '\n';
				db tm = o1.imag() / -v.imag();

				if((o1 + v * tm).real() <= d) {
					r = mid;
					ans = std::min(ans, T + abs(o1 - cp(d, 0)) / V / 2);
				} else {
					l = mid;
				}
			}
			printf("%.20Lf\n", ans);
		} else {
			printf("%.20Lf\n", (d - R) / v);
		}
	}
}