What exactly is the relative angle?

[SoumiDas]

Hi,
As we know the orientation of the car is given in Cartesian coordinate form. Can you kindly clarify me on this part whether the 'relative angle' affordance is calculated from the orientation value? If it is, how do we do that exactly?
Or, can we take the yaw value as the relative angle?

Looking forward to your reply!

Thanks,
Soumi.