Sangakus

Plate 8.1. The illustration from Uchida Kyo¯’s 1832 collection Kokon Sankan, for a problem that was originally proposed in 1822 by Yazawa Hiroatsu on a tablet hung at the Samukawa shrine of Ko¯zagun, Kanagawa prefecture. The result is known in the West as the Soddy hexlet theorem. (Aichi University of Education Library.)