As follows:
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math~~~~~~`
2010-01-31 8:55 pm
回答 (1)
2010-01-31 9:06 pm
✔ 最佳答案
ㄥBAC = 180-75-45=60°ㄥBOC = 2ㄥBAC = 120°
Let the mid point of BC be M :
ㄥBOM = 120/2 = 60°
(BC/2) / BO = sin 60°
3 / r = sin 60° = √3/2
r = 2√3 cm
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原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100131000051KK02581