#include <bits/stdc++.h>
using namespace std;

int T;
double D_avg, d_min;

double f(double x, double r) {
    double Y = sqrt(r*r - x*x), a = r+d_min-x, tmp = sqrt(a*a + Y*Y);
    return 0.5 * (Y * tmp + a*a * log((Y + tmp) / a));
}

double g(double x, double r) {
    double L = r+d_min-x, tmp = r+d_min;
    double theta = acos((-r*r + L*L + tmp*tmp) / (2*L*tmp));
    return L * L * theta;
}

double getavg(double r) {
    int divs = 10000;
    double h = 2*r/divs, V = 0.0;
    for(double x=-r; x<=r; x+=h)
        V += g(x, r);  // or f(x, r)
    V *= 2.0 * h;
    return V / (M_PI * r * r);
}

double solve() {
    double hi = D_avg, lo = 0.0, mid, eps = 1e-5;
    while(hi - lo > eps) {
        mid = (lo + hi) / 2.0;
        if(getavg(mid) < D_avg)
            lo = mid;
        else
            hi = mid;
    }
    return mid;
}

int main() {
    ios_base::sync_with_stdio(false); cin.tie(NULL);

    cin >> T;
    cout.precision(4);
    cout << fixed;
    while(T--) {
        cin >> D_avg >> d_min;
        cout << solve() << "\n";
    }

    return 0;
}