public boolean equals(Object other) {
    	if (!(other instanceof Circle)) {return false;}
    	else
        {
            Circle otherCircle = (Circle) other;
            return ((this.centerX == otherCircle.centerX) &&
                    (this.centerY == otherCircle.centerY) &&
                    (Math.abs(this.radius - otherCircle.radius) < 0.0001));
        }
    }