在另外的地方作一等腰直角三角形,斜邊就是圓O半徑R。直角邊就是 (2^.5/2)R.

來源: jinjing 於 2011-11-21 16:21:20 [舊帖] [給我悄悄話] 本文已被閱讀：次

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