晴天日記這個世界，沒有想像中的簡單，也沒想像中的那麼困難。

http://help.adobe.com/zh_TW/ActionScript/3.0_ProgrammingAS3/WS5b3ccc516d4fbf351e63e3d118a9b90204-7dca.html

import flash.geom.*;
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);