如果cosx+cosy-cos(x+y)=1.5,x,y为锐角,求x和y.
已知sinx-siny=1/2,cosx-cosy=1/2,x、y均为锐角,求sin(x-y)
三角函数的恒等变换已知cos(x+y)=-3/5 cosx=2/3 x y为锐角 求cosy?题中的xy就是 啊而发 和
已知x,y,z均为锐角,且sinx+sinz=siny,cosx-cosz=cosy,求x-y的值.
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)
若cos(x+y)cosy+sin(x+y)siny=0,则cosx=
Sinx+siny=根号2 Cosx+cosy=二分之根号三 求cos(x减y)和cos(x+y)
已知cos(x-y)cosx+sin(x-y)sinx=3/5,则cosy的值为
已知sinx+siny=1/3,cosx-cosy=1/5,求cos(x+y),sin(x-y).