设z=x^2siny-y^2cosx 求偏z/偏X

设z=x^2siny-y^2cosx 求偏z/偏X 已知x,y,z属于(0,派/2),sin^2x+sin^2y+sin^2z=1,求(sinx+siny+sinz)/(cosx+cosy+cosz)的最大值 设cosx+cosy=1/2,sinx+siny=1/4,求cos(x-y)的值 设cosX+cosY=1/2,sinX+sinY =1/4,求cos（X-Y）的值 已知cosx+siny=1/2,求z=asiny+cos²x的最大值 证明.（sinx+siny)/cosx-cosy=ctg(y-x)/2 求过程cosx+siny=1/2 求siny-cos²x的最值 sinx+siny=2/5,cosx+cosy=6/5,求cos(2x-2y) 已知cosx+cosy=1/2,sinx-siny=1/3,求cos(x+y) sinx+siny=-1/3 cosx+cosy=1/2,求sin(x+y)的值. 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 设Z=x^2+siny,x=cost,y=t^3,则dz/dt=? 证明cosx-cos(x+2y)/2siny= sin(x+y)证明cosX-cos(x+2y)/2siny= sin(x+y) 求z=xy+(x^2)siny的二阶偏导数 已知sinx-siny=1/2,cosx-cosy=1/2,x、y均为锐角,求sin(x-y) 设siny+e^3x-2x^3y^2=0,求dy/dx 已知sinx+siny+sinz=cosx+cosy+cosz=0,求tan(x+y+z)+tanxtanytanz的值