#include <bits/stdc++.h>

#pragma GCC optimize("fast-math")

using namespace std;
#define ll long long
#define pii pair<int, int>
#define ld long double
#define all(a) (a).begin(), (a).end()

const ld pi = atan2l(1, 0) * 2;
const int T = 4000000;

ld pre3sin[T];

ld presin[T];
ld precos[T];


ld get_dphi(int phi, ld u, ld r) {
    return (- u * presin[phi] + sqrtl(u * u * pre3sin[phi])) / (2 * r);
}

ld rush(int phi, ld r, ld v, ld d, ld t) {
    d -= 2 * r + t * v;

    ld x = - 2 * r * precos[phi];
    ld y = 2 * r * presin[phi];

    ld x1 = d - x;
    ld y1 = y;

    ld l = sqrtl(x1 * x1 + y1 * y1);
    ld fac = 2 * v / l;

    x1 *= fac;
    y1 *= fac;

    x1 -= v;

    if (x1 * x > y * y1 - 1e-7) {
        // cerr << l << '\n';
        return l / (2 * v);
    } else {
        return -1;
    }
}

void solve() {
    ld u, r, d;
    
    // u = 2.0;
    // r = 3;
    // d = 30;

    cin >> u >> r >> d;

    ld cur_t = 0;
    for (int i = 0; i < T; ++i) {
        // cur phi = pi * i / T
        
        if (cur_t * u > (d - 2 * r)) {
            break;
        }

        if (i * 2 > T) {
            ld ost = rush(i, r, u, d, cur_t);
            if (ost >= 0) {
                // cerr << 
                cout << min(cur_t + ost, (d - r) / u) << '\n';
                return;
            }    
        }

        ld dphi = get_dphi(i, u, r);  // at further point better
        cur_t += pi / T / dphi;

        // ld phi = pi * i / T;
        // cerr << phi / pi * 180 << '\n';
        // cerr << cur_t << '\n';
    }

    cout << (d - r) / u << '\n';
}

signed main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);


    for (int i = 0; i < T; ++i) {
        presin[i] = sinl(pi * i / T);
        precos[i] = cosl(pi * i / T);
        pre3sin[i] = presin[i] * presin[i] + 3;
    }

    cout << fixed << setprecision(15);

    int t = 1000;
    cin >> t;
    while (t--) solve();


    return 0;
}