#include<bits/stdc++.h>
using namespace std;
typedef long double ld;
const long double eps=1e-9;

int T;
int read()
{
    int r=0, f=1; char ch=getchar();
    while(ch<'0'||ch>'9') {if(ch=='-') f=-1; ch=getchar();}
    while(ch>='0'&&ch<='9') {r=r*10+ch-'0'; ch=getchar();}
    return r*f;
}
int main()
{
    // freopen("testdata.in","r",stdin);
    T=read();
    while(T--)
    {
        ld x11,y11,x12,y12,x21,y21,x22,y22;
        cin >> x11 >> y11 >> x12 >> y12;
        cin >> x21 >> y21 >> x22 >> y22;
        ld X1=(x11+x12)/2, Y1=(y11+y12)/2, X2=(x21+x22)/2, Y2=(y21+y22)/2;
        // cout << X1 << " " << Y1 << " " << X2 << " " << Y2 << '\n';
        ld r=(y22-y21)*(y22-y21)+(x22-x21)*(x22-x21);
        r/=8;
        ld NX=X2-sqrt(r), NY=Y2-sqrt(r);
        // cout << man << " " << d << " " << r << '\n';
        cout << fixed << setprecision(10) << abs(NX-X1)+abs(NY-Y1) << '\n';
    }
    return (0-0);
}