i did some of that stuff for a little while as well.
landed bhs, bkicks and a valdez...k so they're not really "tricking" moves per se but i could never find a gym to practice properly. Might start that back up at uni.
"Now Angle PAB + Angle PBA = 65 (The best reason I can give for that is that the sum of these two angles is always the same and the limit as P approaches one of the points A or B is the size of that angle)"
i don't really understand this part...