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更新1:
我想要proof.
CE Maths 2009
2009-04-29 6:57 am
回答 (2)
2009-04-29 7:50 am
✔ 最佳答案
Triangle BEA ~ Triangle CED {angle in same segment + alt angle}So, CD/AB = DE/AE
also ADE is right angle , so cosT = DE/AE
2009-04-29 8:41 am
prove什麼!?
收錄日期: 2021-04-22 00:34:34
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20090428000051KK01875