AOJ:0010

gistfile1.java

import java.util.Scanner;
import java.text.DecimalFormat;

public class Main {
	public static void main(String[] args) {
		Scanner scn = new Scanner(System.in);
		int n = scn.nextInt();
		for (int i = 0; i < n; i++) {
			double x1 = scn.nextDouble();
			double y1 = scn.nextDouble();
			double x2 = scn.nextDouble();
			double y2 = scn.nextDouble();
			double x3 = scn.nextDouble();
			double y3 = scn.nextDouble();
			double a = 0;
			double b = 0;
			double c = 0;
			double d = 0;
			double p = 0;
			double q = 0;
			if (y2 - y1 != 0) {
				a = (x1 - x2) / (y2 - y1);
				b = -1;
				p = - (x2 * x2 - x1 * x1 - y1 * y1 + y2 * y2) / (2 * (y2 - y1));
			} else {
				a = 1;
				p = (x1 + x2) / 2;
			}
			if (y3 - y2 != 0) {
				c = (x2 - x3) / (y3 - y2);
				d = -1;
				q = - (x3 * x3 - x2 * x2 - y2 * y2 + y3 * y3) / (2 * (y3 - y2));
			} else {
				b = 1;
				q = (x2 + x3) / 2;
			}
			double delta = a * d - b * c;
			double x = (d * p - b * q) / delta;
			double y = (a * q - c * p) / delta;
			double r = Math.sqrt((x1 - x) * (x1 - x) + (y1 - y) * (y1 - y));
			String xstr = new DecimalFormat("##0.000").format(x);
			String ystr = new DecimalFormat("##0.000").format(y);
			String rstr = new DecimalFormat("##0.000").format(r);
			System.out.println(xstr + " " + ystr + " " + rstr);
		}
	}
}