已知sinx-siny=1/2,cosx-cosy=1/2,x、y均为锐角,求sin(x-y)
已知sinx-siny=1/2,cosx-cosy=1/2,x、y均为锐角,求sin(x-y)
sinx+siny=-1/3 cosx+cosy=1/2,求sin(x+y)的值.
已知cosx+cosy=1/2,sinx-siny=1/3,求cos(x+y)
已知sinx+siny=1/3,cosx-cosy=1/5,求cos(x+y),sin(x-y).
sinx+siny=1/2,cosx+cosy=(根号3)/3,求sin[(x-y)/2]
证明cosx(cosx-cosy)+sinx(sinx-siny)=2sin(x-y)/2
已知x,y,z均为锐角,且sinx+sinz=siny,cosx-cosz=cosy,求x-y的值.
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)=
已知sinx+siny=(√2)/4,cosx+cosy=1/2,求cos(x-y)的值.
已知sinx-siny=-2/3,cosx-cosy=2/3,且x.y为锐角,则tan(x-y)的值为?
sinx+siny=√2/2 cosx+cosy=√6/2 求sin(x+y)求解答.