Originally Posted by
Vessbot
I went back through your post with my quibbling hat on, and couldn't find anything wrong; so I'm curious too what the other 10% is.
I guess it has to do with the level of simplification. My statement is correct as a "first approximation" with simplifying assumptions such as small angles etc. One can always go one step deeper in aerodynamics but a first order of magnitude is good enough here.