#include<cstdio>
#include<iostream>
#include<algorithm>
#include<ctime>
#include<cstring>
#include<string>
#include<queue>
#include<cmath>

#define file(f) freopen(f".in","r",stdin); freopen(f".out","w",stdout)

#define min(a,b) ((a)<(b)? (a):(b))
#define max(a,b) ((a)>(b)? (a):(b))

using namespace std;

const double EPS = 1e-8;
const double INF = 10000 + 10;

int dcmp(double a){
	if(fabs(a) < EPS) return 0;
	else return a < 0 ? -1 : 1;
}

struct R{
	double dat;
	void r(){
		scanf("%lf",&dat);
	}
	void w(){
		printf("%.2lf\n",dat);
	}
	bool operator == (const R c){
		return !dcmp(dat - c.dat);//dat-EPS < c.dat && dat+EPS > c.dat;
	}
	bool operator < (const R c){
		return dcmp(dat - c.dat) == -1;
	}
	bool operator > (const R c){
		return dcmp(dat - c.dat) == 1;
	}
	bool operator >= (const R c){
		return (*this).operator==(c) || (*this).operator>(c);
	}
	bool operator <= (const R c){
		return (*this).operator==(c) || (*this).operator<(c);
	}
	R operator + (const R c){
		R a;
		a.dat = dat + c.dat;
		return a;
	}
	R operator - (const R c){
		R a;
		a.dat = dat - c.dat;
		return a;
	}
	R operator * (const R c) const{
		R a;
		a.dat = dat * c.dat;
		return a;
	}
	R operator / (const R c){
		R a;
		a.dat = dat / c.dat;
		return a;
	}
};
R zero,two,minu;

struct P{
	R x,y;
	void r(){
		x.r(),y.r();
	}
	P operator - (const P c){
		P a;
		a.x = x - c.x,a.y = y - c.y;
		return a;
	}
	P operator + (const P c){
		P a;
		a.x = x + c.x,a.y = y + c.y;
		return a;
	}
	P operator * (const R c){
		P a;
		a.x = x * c,a.y = y * c;
		return a;
	}
	P operator / (const R c){
		P a;
		a.x = x / c,a.y = y / c;
		return a;
	}
	bool operator < (const P c){
		return mo() < c.mo();
	}
	bool operator > (const P c){
		return mo() > c.mo();
	}
	R CP(P c){
		return (x*c.y) - (y*c.x);
	}
	R DP(P c){
		return (x*c.x) + (y*c.y);
	}
	R mo() const{
		R ret;
		ret.dat = sqrt((x.dat * x.dat) + (y.dat * y.dat));
		return ret;
	}
};

struct L{
	P f,t;//from,to
	R k;
	bool p;
	void getk(){
		P v = f+t;
		if(t.mo() == zero) k = zero;
		else if(v.x == f.x){
			p = 1;
			k.dat = INF;
		}
		else{
			p = 0;
			k = (v.y-f.y) / (v.x-f.x);
		}
	}
	void r(){
		P to;
		f.r(),to.r();
		if(to.y < f.y) swap(f,to);
		t = to - f;
		getk();
	}
	bool cr(L c){
		P A1 = f,A2 = f + t,B1 = c.f,B2 = c.f + c.t;
		if(!(min(A1.x,A2.x) <= max(B1.x,B2.x) &&
			 min(B1.x,B2.x) <= max(A1.x,A2.x) &&
			 min(A1.y,A2.y) <= max(B1.y,B2.y) &&
			 min(B1.y,B2.y) <= max(A1.y,A2.y) ))
			return false;
		if((A1-B1).CP(A2-B1) * (A1-B2).CP(A2-B2) > zero ||
		   (B1-A1).CP(B2-A1) * (B1-A2).CP(B2-A2) > zero)
			return false;
		else
			return true;
	}
	P node(L c){
		P A1 = f,A2 = f + t,B1 = c.f,B2 = c.f + c.t;
		R p = (B1-A1).CP(B2-A1) / ((A1-B2).CP(A2-B2) - (A1-B1).CP(A2-B1));
		return (t * p) + f;
	}
};
L X,Y;

void init(L &l1,L &l2);
void work(L l1,L l2);
R work2(L l1,L l2);
R work3(L l1,L l2);

int main(){
#ifndef ONLINE_JUDGE
	file("2826");
#endif
	L l1,l2;
	int T;
	scanf("%d",&T);
	while(T --){
		init(l1,l2);
		work(l1,l2);
	}
	return 0;
}

void init(L &l1,L &l2){
	l1.r();
	l2.r();
	zero.dat = 0.00;
	two.dat = 2.00;
	minu.dat = -1.00;
	Y.t.y.dat = INF,Y.t.x.dat = 0;
}

void work(L l1,L l2){
	R ans;
	if(l1.k == zero || l2.k == zero || (!l1.cr(l2)))//有一条线段平行于x轴或互不相交
		ans = zero;
	else if(l1.p || l2.p)//有一条线段平行于y轴(已经排除了平行和不相交)
		ans = work2(l1,l2);
	else//还剩三种一般情况：同时左(右)斜或一左一右
		ans = work3(l1,l2);
	ans.w();
}

R work2(L l1,L l2){
	if(l2.p) swap(l1,l2);//l1为平行于y轴的线段
    P N = l1.node(l2),v1,v2;
	v1 = l2.f + l2.t - N;
	v2 = l1.f + l1.t - N;
	if(v1.mo() == zero || v2.mo() == zero) return zero;
	R cos = v1.DP(v2) / (v1.mo() * v2.mo());
	P h = (Y.t / Y.t.mo()) * min((v1 * cos).mo(),v2.mo());
	v1 = (v1/v1.mo()) * (h / cos).mo(),v2 = h;
    return max(v1.CP(v2),v1.CP(v2) * minu) / two;
}

R work3(L l1,L l2){
	P N = l1.node(l2);
	if(abs(l1.k.dat) < abs(l2.k.dat)) swap(l1,l2);//l1的更靠近y轴
	P v1,v2;
	L l3 = Y;
	l3.f = N;
	v1 = l1.f + l1.t - N;
	v2 = l2.f + l2.t - N;
	if(v1.mo() == zero || v2.mo() == zero) return zero;
	R cos1,cos2;
	cos1 = v1.DP(l3.t) / (v1.mo() * l3.t.mo());
	cos2 = v2.DP(l3.t) / (v2.mo() * l3.t.mo());
	P h1,h2;
	h1 = (Y.t / Y.t.mo()) * (v1.mo() * cos1);
	h2 = (Y.t / Y.t.mo()) * (v2.mo() * cos2);
	if((v1-h1).mo() >= (v2-h2).mo() && l1.k * l2.k > zero) return zero;
	else{
		l1.t = (l1.t / l1.t.mo()) * min(v1.mo(),(v2.mo() * cos2) / cos1);
		l2.t = (l2.t / l2.t.mo()) * min(v2.mo(),(v1.mo() * cos1) / cos2);
		l3.t = (l3.t / l3.t.mo()) * l1.t.mo() * cos1;
		R r1 = l3.t.CP(l1.t) / two,r2 = l3.t.CP(l2.t) / two,ret;
		ret = r1 - r2;
		return max(ret,ret * minu);
	}
}

记得要加dcmp。。。如果总是WA可以试试在ans上再加一个EPS。。。(血的教训T_T)