Try to derivate Abs function, getting no solution and no error message

Questions
1

Hi!
I’m new here and I’m trying to derivate the following equation:

D[Abs[(a - d) ((g - h) (k - l) - (m - l) (n - h)) + (b - z) ((m - l) (d - o) - (q - o) (k - l)) + (c - k) ((q - o) (n - h) - (g - h) (d - o))]/Sqrt[((g - h) (k - l) - (m - l) (n - h))^2 + ((m - l) (d - o) - (q - o) (k - l))^2 + ((q - o) (n - h) - (g - h) (d - o))^2], n]

Unfortunately, I don’t get any solution or at least a error message. How could I find my mistake? The partial derivative according to other variables is possible. I just don’t get any results for g, n, m and q. I’m using Wolfram Alpha Pro.

2

The function Abs has no derivative in the complex domain. Mathematica leaves its derivative indicated symbolically as Abs'.

Instead of Abs, try RealAbs, which has a derivative in the real domain.