Why are line angles inverse? It’s quite counter intuitive and I’ve never used a program where 360 was not straight up, but having negative angles go clockwise is quite strange. Can this be changed? I looked in the preferences and could not find and option.
Malcolm
It’s based on how Qt handles angle geometry, and no it can’t be changed.
This arrangement matches school desktop math books for Plane Geometry where
0 degrees is along the X-axis from the Origin at (0,0),
then it sweeps counter-clockwise towards the Y axis for 90 degrees,
then back down to the X axis in negative space for 180 degrees,
and down to the Y axis in negative space for 270 degrees,
then up again to close the circle at the X axis for either 360 degrees or 0 degrees, your preference.
Not to mention it would not make sense to have the starting angle a preference as it would render the whole idea of sharing patterns useless if every user could have a different preference. That is - the angle formulas would be a mess. 
Just for reference…
The angular coordinate is specified as φ by ISO standard 31-11 . However, in mathematical literature the angle is often denoted by θ instead. Angles in polar notation are generally expressed in either degrees or radians (2π rad being equal to 360°).
Every protractor I’ve owned has used this system - albeit the 0 and 180 is sometimes reversed, but never 360 at the top, and I’ve been drafting for 45+ years.
I think what @MalcolmM means is (beside the 360/0 point being straight up)… if you have 10° and minus off 20°, then it shows -10° instead of 350°.
Welll that’s because 10 - 20 IS -10… as far as the math parser is concerned. The parser has no concept of inches, degs, etc. It just does the math.
That being said… one of things on my TO DO list is to “normalize” the angle values so it always shows a value between 0 and 360. So in your example the -10 would be normalized to 350deg… 500 would be 140deg, and so on.
Ah! Great! You’re a star 