Question

(1+cos x-sin x)/(1-sin x-cos x)+(1-cos x-sin x)/(1-sin x+cos

Answer 1

原式=((1+cosx-sinx)^2+(1-cosx-sinx)^2)/((1-sinx-cosx)(1-sinx+cosx))

=（1+sin^2(x)+cos^2(x)-2sinx+2cosx-2sinxcosx+1+sin^2(x)+cos^2(x)-2sinx-2cosx+2sinxcosx）/((1-sinx)^2-cos^2(x))

=(4-4sinx)/(2sinx(sinx-1))

当x=2kπ+π/2（k为整数）时,原式无意义

当x≠2kπ+π/2（k为整数）时,原式=-2/sinx