//KeplerTriangle.java
//inscribed and circumscribed circle of equilateral triangle
//inscribed circle radius r, then triangle side is 2r*sqrt(3) and area is 3r*sqrt(3)

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

public class KeplerTriangle extends JApplet {

    int r;
    int stopN;
        
    public void init() {
        String input;

        input = JOptionPane.showInputDialog("Radius of inscribed circle","50");
        r = Integer.parseInt(input);

        input = JOptionPane.showInputDialog("Number of iterations","1");
        stopN = Integer.parseInt(input);
    }

    public void paint ( Graphics g ) {
    	int w = getWidth();
    	int h = getHeight();  
 	int xc = w/2;
 	int yc = h/2;
 	
  	
  	for (int n=1; n<=stopN; n++) {
  	    g.drawOval(xc-r*n,yc-r*n, 2*r*n,2*r*n);   //inscribed circle	
  	
 	    g.drawLine(xc,yc-2*r*n, (int)(xc-r*Math.sqrt(3)*n),yc+r*n);
  	    g.drawLine((int)(xc-r*Math.sqrt(3)*n),yc+r*n, (int)(xc+r*Math.sqrt(3)*n),yc+r*n);
  	    g.drawLine((int)(xc+r*Math.sqrt(3)*n),yc+r*n, xc,yc-2*r*n);
  	
  	    //circumscribed circle has radius 2r
  	    g.drawOval(xc-2*r*n,yc-2*r*n, 4*r*n,4*r*n);   //circumscribed circle	
  	}

    }
}