class Vector2D {

	public void rotate(double angle) {
		double currentAngle = Math.atan2(y, x);
		double magnitude = Math.sqrt(x * x + y * y);

		x = magnitude * Math.cos(angle + currentAngle);
		y = magnitude * Math.sin(angle + currentAngle);
	}

	public  Vector2D(double x, double y);

}