Can I check whether a player is behind a mob?

I am building a Adventure map and I want to include a Backstab-like feature, where when player is behind "Mob" he is given a diamond sword with sharpness 99999. If he is not, the sword is removed. (Sword will have a durability of 1 so it breaks when you use it)
Is that possible in any way?
Best Answer
Yes, but you need a lot of command blocks. The more you'll have, the more accurate this will be. Basically you need to have a command block for every mob rotation or so.
For example:
The first command block checks if the player is meeting the requirements while the mob is facing the 0 to 5 degree y rotation.
The second command block checks if the player is meeting the requirements while the mob is facing the 5 to 10 degree y rotation.
The third command block...
...
...
...The < insert big number here > command block checks if the player is meeting the requirements while the mob is facing the 355 to 360 (=0) y rotation.
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