c# - How to make my monster face the right direction? -

I have a problem facing my monster in the right direction. Here's my code:

  Zero Rotatmunster (monster monster) {float deltaX = monster.Target.X - monster.coordinate.x; Boat Delta Y = Monsters. aim. Y - Monster. Flag tangetable = deltaax / delta; Demon. Rotation = (Float) Math Atan (tangents); }   
 The problem I am facing is that sometimes the monster moves backwards, it can tilt in the wrong direction, will someone please explain to me what I do I am wrong?  
  
 
 
 you  deltaX  and  deltaY  values ​​symbol To determine what to do with the result of  ethan  method  
  etan  method is not known that you have to calculate positive or negative The values ​​are used tangent, eg it can not tell the difference between  100/50  and  -100 / -50  For some combinations you need to add half rotation to the angle.  
 Which values ​​do not really hold on to me, but basically something like this:  
  float angle = (float) monastery. Atan (tangents); If ((deltaax and lieutenant; 0 & amp; amp; deltaa = gt; = 0) || (deltax> = 0 & amp; amp; amp; amp; amp; amp; amp; amp; amp; amp; amp; amp; amp; amp; amp; amp; amp; amp; amp; amp; amp; amp; amp; amp; amp; amp; amp; Delta \ lt; 0) ) {Angle = angle + monastery PI; } Demon. Rotation = angle;   
 ... or some other combination of positive and negative values, you should be able to find out what gives you the right result for your coordination system.