cos4x/(1+sin4x)=1/5,则tanx=?
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cos4x/(1+sin4x)=1/5,则tanx=?
cos4x/(1+sin4x)=1/5,则tanx=?
cos4x/(1+sin4x)=1/5,则tanx=?
cos4x/(1+sin4x)
=(cos^22x-sin^22x)/(sin2x+cos2x)^2
=(cos2x-sin2x)/(cos2x+sin2x) 分子分母同时除以 cos2x
=(1-tan2x)/(1+tan2x)
=1/5
tan2x=2/3
=2tanx/(1-tan^2x)
tan^2x+3tanx-1=0
tanx=(-3±√13)/2