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共回答了1627个问题 举报
∫(1/tanx)·lntanx dtanx
=lntanx -∫ tanx [ (secx)^2/(tanx)^2 - (secx)^2lntanx/(tanx)^2 ] dx
=lntanx -(1/2)∫ [csc2x - (secx)^2. lntanx/ tanx ] dx
=lntanx -(1/4)ln|csc2x- cot2x| -(1/4)∫ d (lntanx)^2
=lntanx -(1/4)ln|csc2x- cot2x| -(1/4)(lntanx)^2 + C
1年前
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