sin(x-y)cosy+cos(x-y)siny=?
若cos(x+y)cosy+sin(x+y)siny=0,则cosx=
已知cos(x+y)cosy+sin(x+y)siny=4/5,求tanx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sin(x-y)cosy+cos(x-y)siny≥1,则x,y的范围分别是
已知sinx+siny=1/3,cosx-cosy=1/5,求cos(x+y),sin(x-y).
已知sinx+siny=(√2)/4,cosx+cosy=1/2,求cos(x-y)的值.
若sinx-siny=-1/3,cosx-cosy=1/2,则cos(x-y)=?
已知sinx+siny+sinz=0,cosx+cosy+cosz=0 则cos(x-y)=______ 要详解
已知sinx+siny=0.4,cosx+cosy=1.2,则cos(x-y)=______.
设cosX+cosY=1/2,sinX+sinY =1/4,求cos(X-Y)的值
已知sinx-siny=-1/3,cosx-cosy=1/2,求COS(X—Y)=
求证:sin(x-y)/(sinx-siny)=cos[(x-y)/2]/cos[(x+y)/2]