The KaiFangFa開方法 of traditional mathematics was completed in ${\ll}$JiuZhang SuanShu九章算術${\gg}$ originally, and further organized in Song宋 $Yu{\acute{a}}n$元 dinasities. The former is the ShiSuoKaiFangFa釋鎖開方法 using the coefficients of the polynomial expansion, and the latter is the ZengChengKaiFangFa增乘開方法 obtaining the solution only by some mechanical numerical manipulations. ${\ll}$SanHak JeongEui算學正義${\gg}$ basically used the latter and improved the estimate-value array by referring to the written-calculation in ${\ll}$ShuLi JingYun數理精蘊${\gg}$. As a result, ZengChengKaiFangFa was more refined so that the KaiFangFa algorithm is more consistent.

This study aims to analyze Pardies' ${\ll}$Elements of geometry${\gg}$. This book is very interesting from the perspectives of mathematical history as well as of mathematical education. Because it was used for teaching Kangxi emperor geometry in the Qing Dynasty in China instead of Euclid's which was considered as too difficult to study geometry. It is expected that this book suggests historical and educational implications because it appeared in the context of instruction of geometry in the seventeenth century of mathematical history. This study includes the analyses on the contents of Pardies' ${\ll}$Elements of geometry${\gg}$, the author's advice for geometry learning, several geometrical features, and some features from the view of elementary school mathematics, of which the latter two contain the comparisons with other authors' as well as school mathematics. Moreover, some didactical implications were induced based on the results of the study.

Pythagorean thoerem exists in several equivalent forms in the Euclidean plane, that is, the Hilbert plane which in addition satisfies the parallel axiom. In this article, we investigate the truthness and mutual relationships of those propositions in various non-Hilbert planes which satisfy the parallel axiom and all the Hilbert axioms except the SAS axiom.