About angles
Castle Don;
The AoA of most large airplanes is defined as the angle between the (undisturbed) airflow and the airplane's longitudinal reference axis, and is correctly shown in mm43's super graphic.
Just to confuse things a little, D.P. Davies' book uses the name "angle of incidence" for that same angle. However, for many others "angle of incidence" is the angle between the "wing chord" and the longitudinal reference axis. That angle may be meaningful for light aircraft with a straight, constant section, untwisted wing. It is not meaningful for the swept, twisted wings with variable section that are used on modern large transport aircraft. If you want to apply it to the airfoil section in mm43's drawing, the angle of incidence of the horizontal tail as drawn is -13 degrees.
When talking about two-dimensional flow about airfoil sections, it is customary to define AoA as the angle between the airflow and the section chord. However, when talking about the AoA of the tailplane, one should be aware that the airflow at the tail is not undisturbed. A lift-producing wing has a downwash behind it, and therefore the local AoA is less than the free-stream AoA.