how to do?
2008-02-04 2:53 am
回答 (1)
2008-02-04 3:22 am
✔ 最佳答案
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Let ∠ACB=x
∠ABC=∠ACB=x ( base ∠s, isos. △)
∠CDA+∠ABC=90o (ext. ∠ of △)
∠CDA=90o-∠ABC=90o-x
∠ACD+∠ACB+90o=180o (adj. ∠s on st. line)
∠ACD=90o-∠ACB=90o-x=∠CDA
∴AC=AD=AB(sides opp. equal ∠s)
Therefore,AD=AB
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原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080203000051KK02559