check if front left, front right, back right, back left, Angle of two transforms?

how do you check if enemy is on back left of the character something like that i really want to know how its done
something like
if(withn 0 and 90)//front right
if(within 90 and 180)//back right
if(within 180 and 270)//back left
if(within 270 and 360)//front left

You can transform your enemy’s position into local coordinates. Things with a negative ‘z’ will be behind the pivot position. Things with negative ‘x’ will be on the left. Here is a bit of code to demonstrate. It assumes that when the rotation is (0,0,0), the front of your object is facing positive ‘z’. Play with in a new scene to start. Attach it to an object, create a target object in the scene, then drag and drop the target object on the ‘target’ variable in the script. While running, move the target object around the scene.

#pragma strict

var target : Transform;

function Update() {
    var output : String;
	var pos = transform.TransformPoint(target.position);
	if (pos.z < 0) 
		output = "Back ";
		output = "Front ";
	if (pos.x < 0)
		output += "Left";
	    output += "Right";

For future reference clarity , as you already stated , you should use InverseTransformPoint to transform to local space:

Vector3 local_pos = transform.InverseTransformPoint(camera.transform.position);
if (local_pos.z < 0) 
  Debug.Log ("Back ");
  Debug.Log ("Front ");

if (local_pos.x < 0)
  Debug.Log ("Left ");
  Debug.Log ("Right ");