ln tan ½x 的导数怎么求

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见上清滑信陪图答坦腊

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y= ln√卖型tanx
=(1/2)lntanx
y'巧袭
= (1/2) [ 1/孝配兄tanx](secx)^2
=1/(2sinx.cosx)
=1/sin2x

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