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唔該呀 .....
Math 一問....
2008-05-07 12:37 am
回答 (1)
2008-05-07 2:02 am
✔ 最佳答案
cos θ=tan 315 + sin 150
=-tan 45 + sin 30
=-1+1/2
=-1/2
θ=120
2sinθ=tanθ
2sinθ=sinθ/cosθ
2sinθcosθ=sinθ
sinθ(2cosθ-1)=0
sinθ=0 or cosθ=1/2
θ=0,180,60
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原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080506000051KK01335