Java - outputting wrong result?

Question

Java

Why is the result variable equal to 0?

public class Point2{
    private int x;
    private int y;
    public Point2(){
        x=y=0;
        System.out.println("Конструктор без параметров, х = " + x + " y = " + y);
    }
    public Point2(int x0, int y0){
        this.x = x0;
        this.y = y0;
        System.out.println("Конструктор с параметрами , х = " + x + " y = " + y);
    }
    public double dist(){
        double a, b, r;
        a = x * x;
        b = y * y;
        r = Math.sqrt(a + b);
        System.out.println("Расстояние от (0,0) до (" + x + ", " + y + " ) =" + r);
        return r;
    }
    public double distBetween(Point2 p){
        double a, b, r;
        a = x - p.x;
        b = y - p.y;
        r = Math.sqrt(a * a + b * b);
        System.out.println("Расстояние от (" + x + ", " + y + " ) до (" + p.x + ", " + p.y + " ) =" + r);
        return r;
    }
    public static double gerouneArea(double a, double b, double c){
        double ar, p;
        p = (a + b + c) / 2;
        ar = Math.sqrt((p - a) * (p - b) * (p - c));
        return ar;
    }
}

public class Test5a{
    public static void main(String[] args){
        Point2[] point = new Point2[3];
        point[0] = new Point2(1, 2);
        point[1] = new Point2(7, 4);
        point[2] = new Point2(4, 3);
        double d = point[0].dist();
        double d1 = point[0].distBetween(point[1]);
        double d2 = point[1].distBetween(point[2]);
        double d3 = point[2].distBetween(point[0]);
        
        double result = Point2.gerouneArea(d1, d2, d3);
        System.out.println("Square of triange is equal: " + result);
    }
}

Answer 1

Great selection of spots! They lie on the same line, so the area is indeed 0.