AS3 二點間角度計算

function getAngle (startX:Number, startY:Number, endX:Number, endY:Number):Number
{
    var dX:Number = endX - startX;
    var dY:Number = endY - startY;
var ag=Math.atan2(dY,dX) * (180 / Math.PI)
    return ag+90 ;
}