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求值(1+cotx-cscx)(1+tanx+secx)
人气:109 ℃ 时间:2020-06-26 08:42:58
解答
(1+cotx-cscx)(1+tanx+secx)
=(1+cosx/sinx-1/sinx)(1+sinx/cosx+1/cosx)
=[(sinx+cosx-1)/sinx][(cosx+sinx+1)/cosx]
=(sinx+cosx-1)(cosx+sinx+1)/(sinxcosx)
=[(sinx+cosx)-1][(sinx+cosx)+1]/(sinxcosx)
=[(sinx+cosx)^2-1]/(sinxcosx)
=[(sinx)^2+2sinxcosx+(cosx)^2-1]/(sinxcosx)
=(1+2sinxcosx-1)/(sinxcosx)
=2sinxcosx/(sinxcosx)
=2
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