e的h次方=secx 為什等於 e的-h次方=cosx?
回答 (3)
2015-10-07 8:21 pm
✔ 最佳答案
e^h=sec xh=ln sec x
-h=-ln sec x
-h=-ln (1/cos x)
-h=-(ln 1 - ln cos x)
-h=-(0 - ln cos x)
-h=ln cos x
e^-h=cos x
2015-10-08 2:35 am
因為 sec x = 1 / cos x = [ cos x ]⁻¹
e^h = sec x = [ cos x ]⁻¹
則 e^-h = cos x
e^h = sec x = [ cos x ]⁻¹
則 e^-h = cos x
2015-10-07 3:36 pm
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收錄日期: 2021-05-03 14:54:32
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20151007072619AAxDiCv