Vector question left or right side hit detection


I suck at math and especially vector math. I’m trying to detect if something is hit on the left or right side depending on its forward vector.

How do I do this in the most easy way possible?

I have tried with dotproduct between forward vector and hit vector but that gives insanely weird number, not positive or negative. I also tried making that result from dot product with acosd to get degrees but that also doesnt give me positive or negative, again weird numbers. o_O

What I kinda want is like depending on forward vector it can go 180 degrees negative (left side) en 180 degrees right side (positive). So left side hit is for example -70 degrees en right side hit is for example +70 degrees.