Can someone point me to the type of math that is need to handle this.

I have two examples. Top left and lower right.

I have an enemy in red, its view direction is the black line. Then have the player in Blue, with their view direction being the black line.

I’ve done a dot product of the two directions to get the angle between the two people. But What I’m looking for also, to determine if I’m on their left side vs. right side.

I don’t know the math for that.