Circles and Triangles

How can I draw the triangle inside the ellipse with 3 mouse clicked(or how can i do an outside triangle circle with 3 mouse clicked)?? This is my code for triangle with 3 mouse Clicked but I don't know how to put it in the circle(or ellipse).Can somebody help me please??

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import java.awt.geom.*;

public class TriangleComponent extends JComponent
{   private int[] positionX;
    private int[] positionY;
    private int clicks; 
    public TriangleComponent()
    { JFrame f=new JFrame();
        f.getContentPane().add(this);
       f.setSize(640, 480);
      f.setVisible(true);
      clicks = 0;
      MouseListener listener = new MouseTriListener();
      addMouseListener(listener);
      positionX = new int[3];
      positionY = new int[3];
    }

    public void paintComponent(Graphics g)
    {
        Graphics2D g2 = (Graphics2D) g;
        Point2D.Double r1 = new Point2D.Double(positionX[0], positionY[0]);
        Point2D.Double r2 = new Point2D.Double(positionX[1], positionY[1]);
        Point2D.Double r3 = new Point2D.Double(positionX[2], positionY[2]);

        Line2D.Double post1 = new Line2D.Double(r1, r2);
        Line2D.Double post2 = new Line2D.Double(r2, r3);
        Line2D.Double post3 = new Line2D.Double(r3, r1);

        g2.draw(post1);
        g2.draw(post2);
        g2.draw(post3);
    }

        class MouseTriListener implements MouseListener
        {
            public void mousePressed (MouseEvent event)
            {
                positionX[clicks] = event.getX();
                positionY[clicks] = event.getY();
                clicks++;
                if (clicks % 3 ==0)
                {
                    repaint();
                    clicks = 0;
                }
            }

            public void mouseReleased(MouseEvent event) {}
            public void mouseClicked(MouseEvent event) {}
            public void mouseEntered(MouseEvent event) {}
            public void mouseExited(MouseEvent event) {}
        }
          public static void main(String[] args)
            {
             new TriangleComponent();
            }


}