english: If you look at the angles around the fold, you find that if you number the angles in a circle, all the even-numbered angles add up to a straight line, all the odd-numbered angles add up to a straight line.
non_english: Če kote v zgibu oštevilčimo v krogu, opazimo, da koti z sodimi števili tvorijo ravno črto in isto je s koti z lihimi števili.