(cosx)^y=(siny)^x对X求导?

(cosx)^y=(siny)^x对X求导? 求证：tan(x+y)+tan(x-y)=sin2x/cosx*cosx-siny*siny 证明sinx+cos(x+y)siny/cosx-sin(x+y)siny=tan(x+y) 设z=x^2siny-y^2cosx 求偏z/偏X 为什么sinx*cosy-cosx*siny=sin(x-y) 证明.（sinx+siny)/cosx-cosy=ctg(y-x)/2 已知cosx+cosy=1/2,sinx-siny=1/3,求cos(x+y) cosx-cosy=4/1,sinx-siny=3/1求cos(x-y) sinx+siny=2/5,cosx+cosy=6/5,求cos(2x-2y) 已知sinx+siny=0.4,cosx+cosy=1.2,求cos(x-y) sinx+siny=-1/3 cosx+cosy=1/2,求sin(x+y)的值. sinx+siny=1/4,cosx+cosy=1/3求tan(x-y) sinx+siny+sinz=0;cosx+cosy+cosz=0;求cos(x-y) 求过程cosx+siny=1/2 求siny-cos²x的最值 已知sinx+siny=1/3,cosx-cosy=1/5,求cos(x+y),sin(x-y).求过程! 已知cosx+siny=1/2,求siny-cos^2x的最值 jijiji~已知cosx+siny=1/2,求siny-cos^2*x的最值 已知sinx-siny=1/2,cosx-cosy=1/2,x、y均为锐角,求sin(x-y)