#include <iostream>

 #include<cstdio>

 #include<cstring>

 #include<algorithm>

 #include<stdlib.h>

 #include<vector>

 #include<cmath>

 #include<queue>

 #include<set>

 using namespace std;

 #define N 100000

 #define LL long long

 #define INF 0xfffffff

 const double eps = 1e-;

 const double pi = acos(-1.0);

 const double inf = ~0u>>;

 struct point

 {

     double x,y;

     point(double x=,double y=):x(x),y(y) {}

 } p[];

 typedef point pointt;

 pointt operator -(point a,point b)

 {

     return pointt(a.x-b.x,a.y-b.y);

 }

 int dcmp(double x)

 {

     if(fabs(x)<eps) return ;

     return x<?-:;

 }

 double cross(point a,point b)

 {

     return a.x*b.y-a.y*b.x;

 }

 bool cmp(point a,point b)

 {

     return a.y>b.y;

 }

 bool intersection1(point p1, point p2, point p3, point p4, point& p)      // 直线相交

 {

     double a1, b1, c1, a2, b2, c2, d;

     a1 = p1.y - p2.y;

     b1 = p2.x - p1.x;

     c1 = p1.x*p2.y - p2.x*p1.y;

     a2 = p3.y - p4.y;

     b2 = p4.x - p3.x;

     c2 = p3.x*p4.y - p4.x*p3.y;

     d = a1*b2 - a2*b1;

     if (!dcmp(d))    return false;

     p.x = (-c1*b2 + c2*b1) / d;

     p.y = (-a1*c2 + a2*c1) / d;

     return true;

 }

 double solve(point p1,point p2,point p3,point p4,point pp,point tp)

 {

     double ans;

     point p11 = point(p1.x,p1.y+);

     if(dcmp(cross(p11-p1,p1-p3))==)

     {

         ans = ;

         //cout<<",";

     }

     else

     {

         if(dcmp(cross(p11-p1,p1-p3))*dcmp(cross(p1-p2,p3-p4))<)

         {

             ans = fabs(cross(p3-pp,tp-pp))/;

             //cout<<",";

         }

         else ans = ;

     }

     return ans;

 }

 int on_segment( point p1,point p2 ,point p )

 {

     double max=p1.x > p2.x ? p1.x : p2.x ;

     double min =p1.x < p2.x ? p1.x : p2.x ;

     double max1=p1.y > p2.y ? p1.y : p2.y ;

     double min1=p1.y < p2.y ? p1.y : p2.y ;

     if( p.x >=min && p.x <=max &&

             p.y >=min1 && p.y <=max1 )

         return ;

     else

         return ;

 }

 int main()

 {

     int t,i;

     cin>>t;

     while(t--)

     {

         for(i = ; i <=  ; i++)

             scanf("%lf%lf",&p[i].x,&p[i].y);

         sort(p+,p+,cmp);

         sort(p+,p+,cmp);

         point pp;

         if(intersection1(p[],p[],p[],p[],pp))

         {

             if(!on_segment(p[],p[],pp)||!on_segment(p[],p[],pp))

             {

                 puts("0.00");

                 continue;

             }

         }

         //cout<<pp.x<<" "<<pp.y<<endl;

         double ans;

         point p1 = point(p[].x-,p[].y),p2;

         point p3 = point(p[].x-,p[].y);

         if(intersection1(p[],p[],p[],p1,p2)&&on_segment(p[],p[],p2))

         {

             ans = solve(p[],p[],p[],p[],pp,p2);

         }

         else

         {

             intersection1(p[],p[],p[],p3,p2);

            // cout<<p2.x<<" "<<p2.y<<endl;

             ans = solve(p[],p[],p[],p[],pp,p2);

         }

         printf("%.2f\n",ans+eps);

     }

     return ;

 }