Help with AS distance

Ok so I have this script:

[SIZE=1]_root.createEmptyMovieClip(“line”,1);[/SIZE]
[SIZE=1]*_root.onMouseDown = function(){
line.moveTo(_xmouse,_ymouse);
line.lineStyle(4,0x11FF11,100);
this.onEnterFrame = function(){
line.lineTo(_xmouse,_ymouse);

}
}
_root.onMouseUp = function(){
this.onEnterFrame = null;
}*[/SIZE]
[SIZE=1]buttonErase.onPress = function(){
_root.line.clear();
}
[/SIZE]
[SIZE=1][/SIZE]
[SIZE=1]Can someone please tell me how to display the lenght of the line in a Dynamic text box?[/SIZE]