#include <bits/stdc++.h>
using namespace std;
template <typename T>
inline T read(){
    T x=0;char ch=getchar();bool fl=false;
    while(!isdigit(ch)){if(ch=='-')fl=true;ch=getchar();}
    while(isdigit(ch)){
        x=(x<<3)+(x<<1)+(ch^48);ch=getchar();
    }
    return fl?-x:x;
}
#define FASTIO ios::sync_with_stdio(false);cin.tie(0);
#define LL long long
#define read() read<int>()
#define LD long double
LD R1,R2,ans;
int x_1,y_1,x_2,y_2;
const int dx[]={-1,-1,1,1};
const int dy[]={-1,1,-1,1};
int main(){
    FASTIO;
    int T;cin>>T;
    while(T--){
        cin>>x_1>>y_1>>x_2>>y_2;
        LD X1=(x_1+x_2)/2.0,Y1=(y_1+y_2)/2.0,R1=sqrt((x_2-x_1)*(x_2-x_1)+(y_2-y_1)*(y_2-y_1))/2.0;
        cin>>x_1>>y_1>>x_2>>y_2;
        LD X2=(x_1+x_2)/2.0,Y2=(y_1+y_2)/2.0,R2=sqrt((x_2-x_1)*(x_2-x_1)+(y_2-y_1)*(y_2-y_1))/2.0;
        LD base=R2/sqrt(2);
        LD ans=1e9;
        for(int i=0;i<4;i++){
            LD x=X2+base*dx[i],y=Y2+base*dy[i];
            //cout<<x<<' '<<y<<'\n';
            ans=min(ans,fabs(x-X1)+fabs(y-Y1));
        }
        cout<<fixed<<setprecision(9);
        cout<<ans<<'\n';
    }
}