sinx+siny=√2/2 cosx+cosy=√6/2 求sin(x+y)求解答.

证明.（sinx+siny)/cosx-cosy=ctg(y-x)/2 sinx+siny=1/3,则siny-(cosx)^2的最大值为?最小值为? 已知sinx+siny=1/3求siny-(cosx)^2的最小值和最大值 已知sinx+siny=1/3求siny-(cosx)^2的最小值 已知sinx+siny=2/3cosx+cosy=2/3,则sinx+cosx的值? 证明cosx(cosx-cosy)+sinx(sinx-siny)=2sin(x-y)/2 已知sinx+siny=√2,cosx+cosy=2√3/3,求tanx*tany sinx+siny=√2/2,求cosx+cosy的取值范围 sinx+siny=√2/2 则cosx+cosy的取值范围是 求y=(sinx)^2-cosx+2最值已知sinx+siny=1/3,求siny-(cosx)^2的最值 sinx+siny=√2/2 cosx+cosy=√6/2 求sin(x+y)求解答. sinx+siny=√2/2 cosx+cosy=√6/2 求sin(x+y)求解答 已知sinx+siny=（√2）/4,cosx+cosy=1/2,求cos（x-y）的值. cosx+cosy=1/2sinx+siny=√3/3,则cos(x-y)的值为 向量a=(cosx,sinx) b=(cosy,siny) 为什么它们的夹角是y-x a=(cosx,sinx)b=(cosy,siny)θ=y-xa+b=(cosx+cosy,sinx+siny)|a+b|=√(2+2cos(x-y))|a-b|=√(2-2cos(x-y)) sinx+siny=2/5,cosx+cosy=6/5,求cos(2x-2y) 若cosx*cosy+sinx*siny=1/3 ,则cos(2x-2y)=? 已知sinx+cosy=根号2/2,求t=cosx+siny的取值范围?