#include <cstdio>
#include <cmath>
using namespace std;

const double eps = 1e-6;

int t;
int X1, Y1, X2, Y2, X3, Y3, X4, Y4, p;

int Cross(int ax, int ay, int bx, int by) { return ax * by - ay * bx; }

int main()
{
    scanf("%d", &t);
    for (int tc = 1; tc <= t; tc++) {
        scanf("%d %d %d %d %d %d %d %d %d", &X1, &Y1, &X2, &Y2, &X3, &Y3, &X4, &Y4, &p);
        int ax = X2 - X1, ay = Y2 - Y1;
        int bx = X3 - X1, by = Y3 - Y1;
        int cx = X4 - X1, cy = Y4 - Y1;
        double res = abs((Cross(bx, by, ax, ay) + Cross(cx, cy, bx, by)) / 2.0l);
        printf("Case #%d: %.2lf\n", tc, double(p) / res + eps);
    }
    return 0;
}