Help with golf game

hi, i’m new of this chat.
Sorry for my english.
i have a problem with my golf game. i don’t know how bounce a ball.
The code of ball is:

 
 
onClipEvent(load){}
onClipEvent(enterFrame){
 if (_root.speed>0) {
 _x +=Math.sin(_root.angle*(Math.PI/180))*_root.speed;
 _y -=Math.cos(_root.angle*(Math.PI/180))*_root.speed;
 _root.speed--;
 if(this.hitTest(_parent._root.muro)){ //bounce with other movieclip
  trace("coll");
  _x -= Math.sin(_root.angle*(Math.PI/180))*_root.speed;
  _y += Math.sin(_root.angle*(Math.PI/180))*_root.speed;
 }
 if(_y<100){ //height of stage
  trace("100");
  _x -= Math.sin(_root.angle*(Math.PI/180))*_root.speed;
  _y += Math.sin(_root.angle*(Math.PI/180))*_root.speed;
  }
 }
}

 

thank you very much