I am a bot rusty of Vec3D Math some help would be nice in relearning it

This will be a bit nerdy sorry for wall of text :(

I want to determine if someone is using AimHacks by Looking at the degree between a point in space (the target entity) and the View RayCast of the Potential Hacker (The Start Point) to find the most optimal angles they can use as a path to get the raycast line to hit that point with a small offset around the point of accuracy but we need to make it a multi point angle because cheats use a thing called MultiPoint that lets them find the best angle between different target points of the body being the head, arms, body, legs/feet. and I don't know if there are existing algorithms that exist that already do that. My Biggest Issue is the game I am making the check for uses a 3D Rectangle as the hurtbox instead of seperate limb hurtboxes so i need to manually select the points in the Rectangle that are where the limbs are in the 3D model