#include <bits/stdc++.h>
using namespace std;

typedef long double db;
const int maxn=100000;
int n;
db x[maxn+50],y[maxn+50];

db gao(db A,db B,db C){
	db res=0;
	for (int i=1;i<=n;i++){
		db diff=A*x[i]*x[i]+B*x[i]+C-y[i];
		res=max(res,diff*diff);
	}
	return res;
}
db solveAB(db A,db B){
	db mn=1e18;
	db mx=-1e18;
	for (int i=1;i<=n;i++){
		db tmp=y[i]-A*x[i]*x[i]-B*x[i];
		mn=min(mn,tmp);
		mx=max(mx,tmp);
	}
	return (mx-mn)*(mx-mn)/4;
}

db solveA(db A){
	db l=-2e6,r=2e6;
	db ans=1e18;
	for (int cc=1;cc<=80;cc++){
		db mid1=(l+l+r)/3;
		db mid2=(l+r+r)/3;
		db res1=solveAB(A,mid1);
		db res2=solveAB(A,mid2);
		if (res1<res2){
			r=mid2;
			ans=min(ans,res1);
		}
		else{
			l=mid1;
			ans=min(ans,res2);
		}
	}
	return ans;
}

db solve(){
	db l=-2e6,r=2e6;
	db ans=1e18;
	for (int cc=1;cc<=80;cc++){
		db mid1=(l+l+r)/3;
		db mid2=(l+r+r)/3;
		db res1=solveA(mid1);
		db res2=solveA(mid2);
		if (res1<res2){
			r=mid2;
			ans=min(ans,res1);
		}
		else{
			l=mid1;
			ans=min(ans,res2);
		}
	}
	return ans;
}

int main(){
	ios_base::sync_with_stdio(false);
	int T;
	cin >> T;
	for (;T--;){
		cin >> n;
		for (int i=1;i<=n;i++){
			int _x,_y;
			cin >> _x >> _y;
			x[i]=_x;
			y[i]=_y;
		}
		cout << fixed << setprecision(12) << solve() << "\n";
	}
	return 0;	
}