1)if 1-cosy=0.2 and
1)if 1-cosy=0.2 and
1、if sinx-siny= -1/3,cosx-cosy=1/2,then cos(x-y)=?
已知sinx+cosy=3/4,cosx+cosy+1/2,求tanx*tany
已知sinx+siny=1/3,求sinx-cosy*cosy的最大值和最小值.
sinx+siny=1求cosx+cosy的范围
cosx+cosy=1,则sinx+siny的范围
xy+cosy-sinx=1,求dy.
cosx+cosy=1/2,sinx-siny=1/3,则cos(x+y)=?
已知cosx+cosy=1/2,sinx-siny=1/3,求cos(x+y)
sinx+siny=1/4,cosx+cosy=1/3求tan(x-y)
sinx+siny=-1/3 cosx+cosy=1/2,求sin(x+y)的值.
cosx-cosy=4/1,sinx-siny=3/1求cos(x-y)