若cosx*cosy+sinx*siny=1/3 ,则cos(2x-2y)=?
若cosx*cosy+sinx*siny=1/3 ,则cos(2x-2y)=?
cosx+cosy=1/2,sinx-siny=1/3,则cos(x+y)=?
若sinx-siny=-1/3,cosx-cosy=1/2,则cos(x-y)=?
已知cosx+cosy=1/2,sinx-siny=1/3,求cos(x+y)
1、if sinx-siny= -1/3,cosx-cosy=1/2,then cos(x-y)=?
已知sinx+siny=1/2,cosx+cosy=1/3,求cos²((x-y)/2)
已知sinx-siny=-1/3,cosx-cosy=1/2,求COS(X—Y)=
sinx+siny=2/5,cosx+cosy=6/5,求cos(2x-2y)
cosx-cosy=4/1,sinx-siny=3/1求cos(x-y)
sinX+sinY=1 cosX+cosY=0 求cos(2X)+cos(2Y)的值
若3sinx*2+2siny*2=1 且3(sinx+cosx)*2+2(siny+cosy)*2=1求cos(2x+2
sinx+siny=-1/3 cosx+cosy=1/2,求sin(x+y)的值.