HW2.2.2

/**
 * The program reads the coordinates of the point from the keyboard 
 * and determines whether it belongs to the triangle or not.
 * 
 * creator of Yaroslava
 */

package com.gmail.thepowerofyar;

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);

		double xA = 0;
		double yA = 0;
		double xB = 4;
		double yB = 4;
		double xC = 6;
		double yC = 1;

		double x;
		System.out.println("Введите координаты точки x");
		x = sc.nextDouble();

		double y;
		System.out.println("Введите координаты точки y");
		y = sc.nextDouble();

		double pointA = (xA - x) * (yB - yA) - (xB - xA) * (yA - y);
		double pointB = (xB - x) * (yC - yB) - (xC - xB) * (yB - y);
		double pointC = (xC - x) * (yA - yC) - (xA - xC) * (yC - y);

		if ((pointA >= 0 && pointB >= 0 && pointC >= 0) || (pointA <= 0 && pointB <= 0 && pointC <= 0)) {

			System.out.println("Точка принадлежит треугольнику");
		} else {
			System.out.println("Точка не принадлежит треугольнику");
			sc.close();
		}

	}

}