How do I check if the mouse is between two angels

Hi

I think the question is so simple

i want the player to be on the up,down.left or right of the window and not just in the middle

and i know how to do that i just want to compare angels of the mouse

so if the mouse is on the left do something

if the mouse is on the right do another thing etc...

but the funny part is i know i should use "is between angels" but i cant get the right angels

by the way i am not totally embarrassed right now

C2 uses an angle setup that is different to the mathematical norm;