求定积分=∫sinx/(1+(tanx)^2)dx(-π/4

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求定积分=∫sinx/(1+(tanx)^2)dx(-π/4
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求定积分=∫sinx/(1+(tanx)^2)dx(-π/4
求定积分=∫sinx/(1+(tanx)^2)dx(-π/4

求定积分=∫sinx/(1+(tanx)^2)dx(-π/4
=∫sinx/(1+(tanx)^2)dx(-π/4=∫sinx(cosx)^2dx(-π/4=-∫(cosx)^2)dsinx(-π/4=-1/3*(cosx)^3(-π/4=0

另一解
f(x)=sinx/[1+(tanx)^2]
f(-x)=-f(-x)
∫[-π/4,π/4] f(x)=∫[-π/4,0]f(x)dx+∫[0,π/4]f(x)dx
=-∫[0,π/4]f(x)dx+∫[0,π/4]f(x)dx=0