Actionscript:

var xp:Number = 0;

var yp:Number = 0;

var t:Number = 0;

var a:Number = 100;

var b:Number = 10;

x = stage.stageWidth / 2;

y = stage.stageHeight / 2;


graphics.lineStyle(0,0x000000);

addEventListener(Event.ENTER_FRAME, onRun);

function onRun(evt:Event):void {

var p:Number = ((a + b)/b)*t

xp = (a + b) * Math.cos(t)  b * Math.cos(p);

yp = (a + b) * Math.sin(t)  b * Math.sin(p);

if (t == 0){

graphics.moveTo(xp, yp);

}else{

graphics.lineTo(xp, yp);

}

t += 0.05;

}
I've messed with Epicycloids in the past  browsing mathworld I decided to create this snippet. It will draw a curve like this:
One Comment
cool,Cheer up