求方程y'+siny+x*cosy+x=0的同届

已知cos(x+y)cosy+sin(x+y)siny=4/5,求tanx的值 sinx+siny=-1/3 cosx+cosy=1/2,求sin(x+y)的值. sinx+siny+sinz=0;cosx+cosy+cosz=0;求cos(x-y) sinX+sinY=1 cosX+cosY=0 求cos(2X)+cos(2Y)的值 已知sinx+siny+sinz=cosx+cosy+cosz=0,求tan(x+y+z)+tanxtanytanz的值 若cos(x+y)cosy+sin(x+y)siny=0,则cosx= 设cosX+cosY=1/2,sinX+sinY =1/4,求cos（X-Y）的值 已知sinx+siny=（√2）/4,cosx+cosy=1/2,求cos（x-y）的值. 设sinX+sinY=1/4,cosX+cosY=1/3,求tan(X+Y)的值.要详解. 设cosx+cosy=1/2,sinx+siny=1/4,求cos(x-y)的值 sinx+siny=1/3 ,cosx+cosy=1/2,求tan(x+y)的值． 已知cosx+cosy=1/2,sinx-siny=1/3,求cos(x+y)