#include<bits/stdc++.h>

using namespace std;

#define endl "\n"

typedef long long ll;

const int N = 1e6 + 100;

int main()
{
	int T;
	cin >> T;
	while (T--)
	{
		double a, b, c, d, e, f, g, h;
		cin >> a >> b >> c >> d >> e >> f >> g >> h;
		double x1 = (a + c) / 2, x2 = (e + g) / 2,
			y1 = (b + d) / 2, y2 = (f + h) / 2;
		cout << setprecision(10) << abs(x1 - x2) + abs(y1 - y2) - sqrt(2 * (x2 - e) * (x2 - e) + 2 * (y2 - f) * (y2 - f)) << endl;
	}
	return 0;
}