Question #3f65b

1 Answer
May 22, 2016

Answer:

It looks like it might be #-1# but I don't know why (yet)...

Explanation:

Here's a diagram:

enter image source here

The green dot represents the intersection of the bisector of #A# with the unit circle.

I have estimated the bisector by eye, so I may well be mistaken, but it seems that the correct answer may be #-1#.