sinx+siny+sinz=0;cosx+cosy+cosz=0;求cos(x-y)
sinx+siny+sinz=0;cosx+cosy+cosz=0;求cos(x-y)
已知sinx+siny+sinz=0,cosx+cosy+cosz=0 则cos(x-y)=______ 要详解
sinx+siny+sinz=0,cosx+cosy+cosz=0,求cos(y-z)的值.
已知sinx+siny+sinz=cosx+cosy+cosz=0,求tan(x+y+z)+tanxtanytanz的值
已知sinx+siny+sinz=0,cosx+cosy+cosz=0,求证cos(x-y)=cos(y-z)=cos(
已知x,y,z均为锐角,且sinx+sinz=siny,cosx-cosz=cosy,求x-y的值.
sinX+sinY=1 cosX+cosY=0 求cos(2X)+cos(2Y)的值
已知cosx+cosy=1/2,sinx-siny=1/3,求cos(x+y)
sinx+siny=2/5,cosx+cosy=6/5,求cos(2x-2y)
sinx+siny=3/5,cosx+cosy=4/5,求cos(x-y)
cosx-cosy=4/1,sinx-siny=3/1求cos(x-y)
已知sinα+sinX+sinY=0,cosα+cosX+cosY=0,则cos(X-Y) 求思路过程.跪谢