Im using the following script to apply damage to my enemies

if(Input.GetButton("Attack")){
         Collider[] cols = Physics.OverlapSphere(transform.position, rang);

foreach (Collider col in cols){

         if(col.tag == "Enemy"){

     // if object has the right tag...
        // assuming the enemy script is called EnemyScript

        EnemyHealth script = col.GetComponent<EnemyHealth>();
        script.AddjustCurrentHealth(-10); // apply damage 5

This works well, but i don't want to attack the enemy if it is behind me. how cab i get the rotation of the object so i can use it in an if statement, or is there another way to do it? Please Help