| It's a special case versus |
| 送交者: 定理 2009月04月11日10:18:52 于 [教育学术] 发送悄悄话 |
| 回 答: What's the difference? 由 要饭花子 于 2009-04-11 09:48:50 |
|
a general case.
among right triangles, two of them are said congruent iff their two sides are respectively of equal length. among arbitrary triangles, two of them are said congruent iff their three sides are respectively of equal length. the former condition is weaker than the latter condition. in other words, Euclid needs to form a definition on a bigger domain of objects, or assume a stronger condition, than Zhou. |
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