I'll agree with you on the Pos/Neg concept. (Never seen this notation before, and ve is not defined in the text, AFAIK.) I'll have to study the 1983 book more...
The book does mention optical quality resolution being "poor" (1983) (Readability). The book states that lower case and upper case identify the same "parameters", for readability.
Putting ve after the + or - makes the symbols stand out...


Attached is a script to calculate the Homothetic point for two circular arcs or circles, in the XZ plane, Front view. It does not work in other views.
y and z get mixed up.
I was unable to get cplane to make it work on other views. It is confusing. I dabbled with cplane, without success.

Time for me to move on, as this is Larry's project :-)
I guess the Homothetic point could be used with the MoI5 beta method mentioned earlier by yourself, to draw inner half tangent lines...

- Brian

It does not matter in which order the two "circles" are selected.