[goodguy]

var circle1Radius:Number = 30;
var circle2Radius:Number = 20;
 
function onEnterFrame(e:Event):void {
       var c1:Point = new Point(circle1.x, circle1.y);
       var c2:Point = new Point(circle2.x, circle2.y);
       if (Point.distance(c1, c2) < circle1Radius + circle2Radius) {
            trace("круги столкнулись");
       }
}