And guess what... I messed up the nomenclature again.

I mistakenly refered to the "bow" ... It should be the curve ADB.
Can I help it if "bow" implies a curve to me!!!

Anyways... I think by now everyone gets the gist. ... I hope...

Interestingly... If you do choose option Chord & Arc and enter 20 and 31.46
respectively then the apotherm is the same as the triangle area....
0.000036732. where... IMHO they should both be zero.