E1

#include <bits/stdc++.h>

using namespace std;

#define cin_2d(vec, n, m) for(int i = 0; i < n; i++) for(int j = 0; j < m && cin >> vec[i][j]; j++);
#define cout_2d(vec, n, m) for(int i = 0; i < n; i++, cout << "\n") for(int j = 0; j < m && cout << vec[i][j] << " "; j++);
#define cout_map(mp) for(auto& [f, s] : mp) cout << f << "  " << s << "\n";
#define Time cerr << "Time Taken: " << (float)clock() / CLOCKS_PER_SEC << " Secs" << "\n";
#define fixed(n) fixed << setprecision(n)
#define ceil(n, m) (((n) / (m)) + ((n) % (m) ? 1 : 0))
#define fill(vec, value) memset(vec, value, sizeof(vec));
#define Num_of_Digits(n) ((int)log10(n) + 1)
#define mod_combine(a, b, m) (((a % m) * (b % m)) % m)
#define all(vec) vec.begin(), vec.end()
#define rall(vec) vec.rbegin(), vec.rend()
#define sz(x) int(x.size())
#define debug(x) cout << #x << ": " << (x) << "\n";
#define fi first
#define se second
#define Pair pair < int, int >
#define ll long long
#define ull unsigned long long
#define Mod  1'000'000'007
#define OO 2'000'000'000
#define EPS 1e-9
#define PI acos(-1)

template < typename T = int > istream& operator >> (istream &in, vector < T > &v) {
    for (auto &x: v) in >> x;
    return in;
}

template < typename T = int > ostream& operator << (ostream &out, const vector < T > &v) {
    for (const T &x: v) out << x << ' ';
    return out;
}

void AhMeD_HoSSaM(){
    ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
    freopen("cross.in", "r", stdin);
    /*#ifndef ONLINE_JUDGE
        freopen("input.txt", "r", stdin), freopen("output.txt", "w", stdout);
    #endif*/
}

double get_time(double a, double b){
    return sqrt(a * a + b * b);
}

void Solve(){
    int h, v, t;
    cin >> h >> v >> t;
    double l = 0, r = h, nearest = 0, nearest_time = v;
    while(r - l > EPS){
        double m = (l + r) / 2;
        double time = get_time(m, v);
        (time <= t ? l = m, nearest = m, nearest_time = time : r = m);
    }
    cout << fixed << setprecision(9) << nearest_time + (h - nearest) << '\n';
}

int main(){
    AhMeD_HoSSaM();
    int t = 1;
    cin >> t;
    while(t--)
        Solve();
    return 0;
}