証明是恆等式
cosxsin(90-x)=1-tanxsinxcosx
a-maths!!!!!!!!
2007-09-09 2:41 am
回答 (2)
2007-09-09 2:47 am
✔ 最佳答案
cosxsin(90-x)= cosx cosx
1-tanx sinxcosx
= 1 - (sinx/cosx) sinxcosx
= 1 - sinx sinx
= cosx cosx
so, L.H.S. = R.H.S.
2007-09-09 2:48 am
LHS
=cosxsin(90-x)
=cosx cosx
=cos^2 x
RHS
=1-tanx sinxcosx
=1-(sinx/cos)sinx cosx
=1-sin^2 x
=cos^2 x
=LHS
So cosxsin(90-x)=1-tanx sinxcosx is Ture
=cosxsin(90-x)
=cosx cosx
=cos^2 x
RHS
=1-tanx sinxcosx
=1-(sinx/cos)sinx cosx
=1-sin^2 x
=cos^2 x
=LHS
So cosxsin(90-x)=1-tanx sinxcosx is Ture
收錄日期: 2021-04-23 20:35:16
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20070908000051KK03999