Как достать из XYChart значения x и y?

XYChart.Series series = new XYChart.Series<>(); 
    ObservableList<XYChart.Data> list = FXCollections.observableArrayList(); 
     
    for (double i = 0; i < 360; i += 0.5) { 
                double radian = i / 57.3; 
                double ro = 2 * a * (1 - Math.cos(radian)); 
                double x1 = ro * Math.cos(radian); 
                double y1 = ro * Math.sin(radian); 
                list.add(new XYChart.Data(x1, y1)); 
            } 
            series.setData(list); 
            chart_zone.getData().addAll(series);