I'm not sure how they got the components of the B-field in the r and θ direction. I know the B-field along the ∅ direction is zero though.
The Attempt at a Solution
Here I have found the B-field at points P, Q and S that are very far along the z, x and y axis. But what about the field at point R, angle θ to the magnetic moment? How do the Bz,∞, By,∞ and Bx,∞ components contribute?