#include <bits/stdc++.h>
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
using namespace std;
typedef long long ll;
typedef long double ld;
const int mod = 1e9 + 7;
const int N = 1e6 + 5;
const ld pi = acos(-1);

void solve() {
	ld v, r, d; cin >> v >> r >> d;
	ld ans = d / v;
	ld tup = 2 * r / v * 1.3116414728929514370;
	if (d - 4 * r - v * 2 * tup >= 0) {
		auto g = [&](ld a) {
			ld ca = cos(a);
			return sqrt(3 + ca * ca) - ca;
		};
		auto g2 = [&](ld a) {
			ld ca = cos(a);
			return sqrt(3 + ca * ca);
		};
		auto int2 = [&](ld hi) {
			int n = 100;
			ld h = hi / n, ret = 0;
			for (int i = 0; i <= n; i++) {
				if (i < n)
					ret += 2 * h / 3 * g2(i * h + h / 2);
				ret += h / 6 * (1 + (i > 0 && i < n)) * g2(i * h);
//				ret += h / 6 * (g2(i * h) + 4 * g2(i * h + h / 2) + g2((i + 1) * h));
			}
			return ret;
		};
		auto integrate = [&](ld hi) {
			return (sin(hi) + int2(hi)) / 3;
		};
		auto f = [&](ld t) {
			ld nd = max(2 * r, d - v * t);
			ld a = asin(2 * r / nd);
			ld tc = integrate(a) * 2 * r / v;
			ld tl = sqrt(nd * nd - 4 * r * r) / (v * g(a));
			return tl + tc <= t;
		};
		d -= 2 * r + v * tup;
		ld lo = tup, hi = d / v;
		for (int it = 0; it < 100; it++) {
			ld m = (lo + hi) / 2;
			if (f(m))
				hi = m;
			else
				lo = m;
		}
		ans = tup + lo;
	}
	cout << fixed << setprecision(10) << ans << "\n";
}

int main() {
	ios_base::sync_with_stdio(false); cin.tie(0);
	int t; cin >> t; while (t--) solve();
}