1-sinx cosx如何化为cosx-sinx ∫1/（sinx+cosx）dx，这题咋做啊？？
cosx-sinx\u600e\u4e48\u5316\u7b80\uff1f sinx-cosx\u600e\u4e48\u5316\u7b80\uff1f\u89e3\u9898\u6b65\u9aa4\u5982\u4e0b
cosx-sinx
=\u221a(cosxcos45\u00b0-sinxsin45\u00b0)
=\u221acos(x+45\u00b0)
sinx-cosx
=\u221a(sinxcos45\u00b0-cosxsin45\u00b0)
=\u221asin(x-45\u00b0)
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\u222b1/\uff08sinx+cosx\uff09dx
=\u222bdx/\u221a2sin(x+\u03c0/4)
=-(\u221a2/2)\u222bdcos(x+\u03c0/4)/sin^2(x+\u03c0/4)
=-(\u221a2/4\uff09{\u222bdcos(x+\u03c0/4)/[1-cos(x+\u03c0/4)]+\u222bdcos(x+\u03c0/4)/[1+cos(x+\u03c0/4)]}
=-(\u221a2/4)ln{[1+cos(x+\u03c0/4)]/[1-cos(x+\u03c0/4)]}+c
=(\u221a2/4)ln{[1-cos(x+\u03c0/4)]/[1+cos(x+\u03c0/4)]}+c
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则：
1－2sinxcosx
=sin²x－2sinxcosx＋cos²x
=(sinx－cosx)²
扩展阅读：r a 1-sinθ 的解析过程 ... r a 1 sinθ 真正画法 ... 1-sin 2x ... r a 1 sinθ 解答求图 ... asinx-bcosx ... sinx化解成1-cosx ... r=a(1-sinθ)怎么画 ... 1-cosx换成sinx ... sinx 2+cosx 2 ...
