ACOS logarithmic form

[Claudio L.]

(04-28-2016 03:07 PM)Claudio L. Wrote:  Here's my dilemma:

I think I figured it out.
I think the formula is right, but the only difference is which branch of the sqrt() you take. For whatever reason, for real numbers the 50g and Wolfram take the negative root, which provides the sign change.
Are there any conventions as far as which branch to take?

If I take an arbitrary number like (2 3), I get the right value, but on reals it goes to the wrong solution (actually I shouldn't say the wrong solution, as both are correct solutions, just goes to "another" solution).