Sign for Included Angle?

It has always baffled me that sometimes the display of the iincluded angle between two lines is negative and sometimes positive. This is unnerving in that you have to double check operations when doing architectural sketches.

I have tried to figure out the logic here. Relative direction from first drawn line? Relative direction in which lines are selected? Some combination thereof?

Why should the included angle ever be negative?

Or is this just random, due to a bug? An explanation would be appreciated.



Mathematically it does make sense, but we shouldn’t display it, you are right.