已知cos(x+y)cosy+sin(x+y)siny=4/5,求tanx的值
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).
已知sinx+siny=(√2)/4,cosx+cosy=1/2,求cos(x-y)的值.
已知tanx=-1/3,cosy=根号5/5,求tan(x+y)的值和函数f(x)=根号2sin(a-x)+cos(a+
1.已知8cos(2x+y)+5cosy=0,求tan(x+y)*tanx的值.
已知sin A+sinB +siny=0 ,cos A+cos B+cosy=0,求cos(B -y)的值.
sinx+siny=-1/3 cosx+cosy=1/2,求sin(x+y)的值.
sinx+siny=3/5,cosx+cosy=4/5,求cos(x-y)
已知sina+sinβ+siny=0,cosa+cosβ+cosy=0,求cos(β-y)的值?
已知3cos(2x+y)+5cosy=0,则tan(x+y)tanx的值是
设cosX+cosY=1/2,sinX+sinY =1/4,求cos(X-Y)的值
设cosx+cosy=1/2,sinx+siny=1/4,求cos(x-y)的值