求不定积分 ∫sin2x/(1+sin^2x)dx 求解!求不定积分 ∫sin2x/(1+sin^2x)dx 求解! 谢谢

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求不定积分 ∫sin2x/(1+sin^2x)dx 求解!
求不定积分 ∫sin2x/(1+sin^2x)dx 求解! 谢谢


 
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sin(2x)/(1+sin²x)
=sin(2x)/[1+(1-cos(2x))/2]
=2sin(2x)/[3-cos(2x)]

∫[sin2x/(1+sin²x)] dx
=∫2sin(2x)/[3-cos(2x)]dx
=∫1/[3-cos(2x)]d(-cos(2x))
=ln[3-cos(2x)] +C

∫sin2x/(1+sin^2x)dx
= ∫2sinxcosx/(1+sin^2x)dx
= ∫2sinxdsinx/(1+sin^2x)
= ∫dsin^2x/(1+sin^2x)
= ln(1+sin^2x) + c