ActionScript 3.0 Note

way 1

function DistanceTwoPoints(x1:Number, x2:Number, y1:Number, y2:Number):
Number {
var dx:Number = x1-x2;
var dy:Number = y1-y2;
return Math.sqrt(dx * dx + dy * dy);
}

way 2

var pt1:Point = new Point(circle1.x, circle1.y);
var pt2:Point = new Point(circle2.x, circle2.y);
var distance:Number = Point.distance(pt1, pt2);