#include <cstdio>
#include <cmath>
#include <cstdlib>
int main() {
    freopen("in.txt", "r", stdin);
    int T,cs=1;
    scanf("%d", &T);
    for (cs = 1; cs<=T; cs++) {
        double  rat, ab, bc, ac,de,ae,ad, ratio, s, area,s2,area2,area3;
        scanf("%lf %lf %lf %lf", &ab, &ac, &bc, &ratio);

        s = (ab+bc+ac)/2;
        area = sqrt(s*(s-ab)*(s-bc)*(s-ac));
        double  low = 10e-7;
        double high = ab;
        int xyz = 100;
        while (xyz--) {
            ad = low + (high-low)/2;
            //printf("%lf %lf %lf\n", low, high,ad);
            de = (ad/ab) * bc;
            ae = (ad/ab) * ac;

            s2 = (ad * (((bc/ab) + (ac/ab) + 1) / 2));

            area2 = sqrt(s2*(s2-ad)*(s2-de)*(s2-ae));
            area3 = area -area2;

            if ((area3*ratio - area2) <= 10e-6) break;
            else if (area3*ratio < area2) {
                high = ad-10e-5;
            }
            else {
                low = ad + 10e-5;
            }
        }
        printf("%lf\n", ad);
    }
    return 0;
}