唔該..有邊個可以計個步驟同個ans比我睇？
prove the following identities
sin^4 x+cos^4 x=1-2sin^2 x cos^2 x
數學高手..請進..
2008-11-14 5:04 am
回答 (2)
2008-11-14 5:24 am
✔ 最佳答案
Prove : sin4x + cos4x = 1 - 2 sin2x cos2xLHS = sin4x + cos4x
= sin4x + 2 sin2x cos2x + cos4x - 2 sin2x cos2x
= (sin2x + cos2x)2 - 2 sin2x cos2x
= (1)2 - 2 sin2x cos2x
= 1 - 2 sin2x cos2x
= RHS
2008-11-13 21:27:55 補充：
補充參考資料：我的數學老師
2008-11-13 21:32:56 補充：
我的數學老師教我sin^2x + cos^2x = 1
2008-11-15 2:40 am
LHS
=sin^4 x+cos^4 x
=(sin^2 x+cos^2x)^2-2sin^2x cos^2x
=1-2sin^xcos^x
=RHS
=sin^4 x+cos^4 x
=(sin^2 x+cos^2x)^2-2sin^2x cos^2x
=1-2sin^xcos^x
=RHS
收錄日期: 2021-04-23 14:49:30
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20081113000051KK01248