The term "bearing angle" sounds too specialized for me. The term "bearing" is used in aviation and other forms of navigation, which is probably where the phrase "bearing angle" comes from. This may also cause some confusion since, in aviation and navigation, angles are measured clockwise from the positive y axis.
Google returns nothing of mathematical significance for "orientation angle". On the other hand, for "direction angle", I found something right away. The Merriam-Webster online dictionary has:
> direction angle
> Function: noun
> an angle made by a given line with an axis of reference; specifically: such an angle made by a straight line with the three axes of a rectangular Cartesian coordinate system -- usually used in plural
If you want to see for yourself, here is the link:
http://www.m-w.com/dictionary/direction+angle
According to this definition, if you declare the "axis of reference" is the positive x axis, then "direction angle" is perfectly fine.
Apparently, "terminal angle" is in usage, but not too much. Moreover, the sites that Google returned with some (albeit minor) mathematical significance only discuss terminal angles and provide no definition or pictures.
So I guess "direction angle" wins!
Warren |
|
![[parent]](http://images.planetmath.org:8080/images/uparrow.png)