I would appreciate if you could have a look at the attached file that  contains the formula for two distances, d(a,B_H) and d(b, A_H). The  final result, D is the maximum of the two distances.In thi

I would appreciate if you could have a look at the attached file that  contains the formula for two distances, d(a,B_H) and d(b, A_H). The  final result, D is the maximum of the two distances.

In this question, the first order derivative of D is needed (differentiated with respect to A_H). I would like to ask if a full solution will be presented, step-by-step, for the first order differentiation?