ABSTRACT
In the business of cartwrights (cheren 1 ), (they) define half a square ju 2 (90°) as an angle xuan 3 (45°), one and a half xuan as an angle zhu 4 (67° 30′), one and a half zhu as an angle ke 5 (101º 15′), one and a half ke as an angle qingzhe 6 (151° 52′ 30″).
