如果cosx+cosy-cos(x+y)=0,x,y为锐角,求x和y.

如果cosx+cosy-cos(x+y)=1.5,x,y为锐角,求x和y. 如果cosx+cosy-cos(x+y)=0,x,y为锐角,求x和y. 三角函数题cosx+cosy=cosxcosy……cosx+cosy=cosxcosy,cos((x+y)/2)=0.8,则cos((x-y)/2)=? 若cos(x+y)cosy+sin(x+y)siny=0,则cosx= 若cosx*cosy+sinx*siny=1/3 ,则cos(2x-2y)=? 已知cosx+cosy=1/2,sinx-siny=1/3,求cos(x+y) cosx+cosy=1/2,sinx-siny=1/3,则cos(x+y)=? cosx-cosy=4/1,sinx-siny=3/1求cos(x-y) sinx+siny=2/5,cosx+cosy=6/5,求cos(2x-2y) 已知cosx+cosy=1/2,sinx-siny=1/3,则cos(x+y)= 已知sinx+siny=0.4,cosx+cosy=1.2,求cos(x-y) sinx-siny=-√3/3 cosx-cosy=-1/3 则cos(x-y) cos(x+y)不等于0,cosx*cosy也不等于0吗 sinx+siny+sinz=0;cosx+cosy+cosz=0;求cos(x-y) sinX+sinY=1 cosX+cosY=0 求cos(2X)+cos(2Y)的值 已知sinx+siny=1/3,cosx-cosy=1/5,求cos(x+y),sin(x-y).求过程! 已知cos(x-y)cosx+sin(x-y)sinx=3/5,则cosy的值为 COSX+COSY-COS(X+Y)=3/2求角X Y分别是多少?谢谢好心的师姐师兄啦.