#include <bits/stdc++.h>

using namespace std;

#define FOR(i, a, b) for(int i = (a); i < (b); i++)
#define RFOR(i, a, b) for(int i = (a) - 1; i >= (b); i--)
#define SZ(a) int(a.size())
#define ALL(a) a.begin(), a.end()
#define PB push_back
#define MP make_pair
#define F first	
#define S second

typedef long long LL;
typedef vector<int> VI;
typedef pair<int, int> PII;
typedef double db;

const int M = 40000;
const db PI = acos(-1.0);
const db EPS = 1e-9;

db v, r, d;

db f(db phi)
{
	db si = sin(phi);
	return -v / (2 * r) * (sqrt(3 + si * si) - si);
}

void solve()
{
	cin >> v >> r >> d;
	db ans = d / v;
	db phi = PI;
	const db dt = ans / M;
	FOR(i, 1, M + 1)
	{
		db t = i * dt;
		db k1 = f(phi), k2 = f(phi + dt / 2 * k1), k3 = f(phi + dt / 2 * k2),
			k4 = f(phi + dt * k3);
		phi += dt / 6 * (k1 + 2 * k2 + 2 * k3 + k4);
		db si = sin(phi);
		if (phi < PI / 2)
		{
			db a = d - 2 * r - v * t;
			if (a < 0)
				continue;
			db l = sqrt(4 * r * r + a * a - 4 * r * a * cos(phi));
			db siBeta = 2 * r * si / l;
			if (siBeta > 1 - EPS)
			{
				return;
			}
			db beta = asin(siBeta);
			if (phi + beta <= PI / 2 && 2 * cos(phi + beta) >= cos(phi))
			{
				ans = min(ans, t + l / (2 * v));
				break;
			}
		}
	}
	cout << ans << "\n";
	//cerr << ans - 8.310579933902352 << "\n";
}

int main()
{
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout << fixed << setprecision(15);
	int t;
	cin >> t;
	while (t--)
		solve();
	return 0;
}