sin(x+y)cosy-cos(x+y)siny求解释
已知cos(x+y)cosy+sin(x+y)siny=4/5,求tanx的值
已知sinx+siny=1/3,cosx-cosy=1/5,求cos(x+y),sin(x-y).
若cos(x+y)cosy+sin(x+y)siny=0,则cosx=
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)
sinx+siny+sinz=0;cosx+cosy+cosz=0;求cos(x-y)
cosx-cosy=4/1,sinx-siny=3/1求cos(x-y)
sinx+siny=-1/3 cosx+cosy=1/2,求sin(x+y)的值.
已知sinα+sinX+sinY=0,cosα+cosX+cosY=0,则cos(X-Y) 求思路过程.跪谢
已知sinx-siny=1/2,cosx-cosy=1/2,x、y均为锐角,求sin(x-y)
已知sin(x-y)cosy+cos(x-y)siny≥1,则x,y的范围分别是