maths~~~~~~~~
2010-04-18 11:29 pm
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回答 (1)
2010-04-19 3:35 am
✔ 最佳答案
BC²=5²+7²−2(5)(7)cos82°BC≈8.01610148 cm
∠BDC=∠BAE=82°
8.01610148 sin∠BCD = 8 sin82° (sine law)
. ∠BCD ≈ 81.21896823°
Let x=∠DBC.
∠CAD = ∠DBC = x
∠BAD = x+82°
∠BCD = 180°−(x+82°) = 98°−x
Because ∠BCD ≈ 81.21896823° ,
∴ 98°−x ≈ 81.21896823°
. x ≈ 16.78103177°
收錄日期: 2021-04-23 20:42:42
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20100418000051KK00956