That's based on the assumption that the two angles in the middle add up to 180, which can't be assumed by inspection alone as demonstrated by the visibly square 80° angle
I learned recently that machinists used to use fractions to indicate tolerance, like a dimension given as 5/16 could be ±1/32 of an inch, because anything less than 9/32 would round to 4/16, and anything more than 11/32 to 6/16.
I don't understand the torture thing, but I think the comment is joking that "bringing in the goat" would mean bringing in LeBron, because he is the G.O.A.T. (greatest of all time)
I freaking love mechanical calculators!