Please help me prove :
1- (sin^2x/1+cosx) = cos x
Trig Identities Help?
2012-05-27 10:07 pm
回答 (2)
2012-05-27 10:15 pm
sin^2x=1-cos^2x
LHS: 1-[(1-cos^2x) / (1+cosx)]
(1+cosx-1+cos^2x) / (1+cosx)
(cos^2x+cosx) / (1+cosx)
cosx(cosx+1) / (1+cosx)
cosx
Hence LHS=RHS as required.
LHS: 1-[(1-cos^2x) / (1+cosx)]
(1+cosx-1+cos^2x) / (1+cosx)
(cos^2x+cosx) / (1+cosx)
cosx(cosx+1) / (1+cosx)
cosx
Hence LHS=RHS as required.
2012-05-27 10:12 pm
1-(1-cos^2x)/(1+cosx)
(1+cosx-1+cos^2x)/(1+cosx)
(cosx+cos^2x)/(1+cosx)
cosx(1+cosx)/(1+cosx)
=cosx
(1+cosx-1+cos^2x)/(1+cosx)
(cosx+cos^2x)/(1+cosx)
cosx(1+cosx)/(1+cosx)
=cosx
收錄日期: 2021-05-01 15:54:16
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https://hk.answers.yahoo.com/question/index?qid=20120527140711AAA8Ek8