開方(2+2cosx) = 3乘開方(2-2cosx)
cosx = ?
點開方兩邊呀?
2011-04-30 3:29 am
回答 (1)
2011-04-30 4:07 am
✔ 最佳答案
√(2 + 2 cosx) = 3√(2 - 2 cosx)2 + 2cosx = 9(2 - 2 cosx)
2 + 2cosx = 18 - 18cosx
20cosx = 16
cosx = 4/5
參考: Knowledge is power.
收錄日期: 2021-04-25 17:07:29
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20110429000051KK01196