∫/(1+sinx+cosx)dx

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∫/(1+sinx+cosx)dx∫/(1+sinx+cosx)dx∫/(1+sinx+cosx)dx设t=tan(x/2),则x=2arctant,sinx=2t/(1+t²),cosx=

∫/(1+sinx+cosx)dx
∫/(1+sinx+cosx)dx

∫/(1+sinx+cosx)dx
设t=tan(x/2),则x=2arctant,sinx=2t/(1+t²),cosx=(1-t²)/(1+t²),dx=2dt/(1+t²)
故 ∫dx/(1+sinx+cosx)=∫[2dt/(1+t²)]/[1+2t/(1+t²)+(1-t²)/(1+t²)]
=∫[2dt/(1+t²)]/[2(1+t)/(1+t²)]
=∫dt/(1+t)
=ln│1+t│+C (C是积分常数)
=ln│1+tan(x/2)│+C.