题目
若tana=3 则1+sin2x+cos2x/1+sin2x-cos2x=
提问时间:2021-03-04
答案
1+sin2x+cos2x/1+sin2x-cos2x
=(2sinxcosx+2cos^2x)/(2sinxcosx+2sin^2x)
=(tanx+1)/(tanx+tan^2x)
=(3+1)/(3+9)
=1/3
1+cos2x=2cos^2x
1-cos2x=2sin^2x
=(2sinxcosx+2cos^2x)/(2sinxcosx+2sin^2x)
=(tanx+1)/(tanx+tan^2x)
=(3+1)/(3+9)
=1/3
1+cos2x=2cos^2x
1-cos2x=2sin^2x
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