#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 = 20000000;


ld get_dphi(ld phi, ld u, ld r) {
    ld sinp = sinl(phi);
    return (- u * sinp + sqrtl(u * u * (sinp * sinp + 3))) / (2 * r);
}

double tphi[T + 2];

void precalc() {
    ld cur_t = 0;
    for (int i = 0; i < T; ++i) {
        ld phi = pi * i / T;
    
        ld dphi = get_dphi(phi, 1, 1);  // at further point better
        cur_t += pi / T / dphi;
        tphi[i + 1] = cur_t;
    }
}

ld get(ld phi, ld v, ld r) {
    ld prop = phi / pi * T;
    int i = floor(prop);

    return r / v * (tphi[i] * (1 - (prop - i)) + tphi[i + 1] * (prop - i));
}

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

    ld x = - 2 * r * cosl(phi);
    ld y = 2 * r * sinl(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;

    cin >> u >> r >> d;

    if (5.246565891571807L * r <= d - 4 * r) {
        ld lp = pi / 2;
        ld rp = pi;

        for (int i = 0; i < 300; ++i) {
            ld mp = (lp + rp) / 2;

            ld t = get(mp, u, r);
            if (rush(mp, r, u, d, t) >= 0) {
                rp = mp;
            } else {
                lp = mp;
            }
        }

        ld t = get(rp, u, r);
        cout << t + max((ld)0, rush(rp, r, u, d, t)) << '\n';

    } else {
        cout << d / u << '\n';        
    }
}

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

    precalc();

    cout << fixed << setprecision(15);

    // cout << get(pi, 1, 1) << '\n';

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


    return 0;
}