sinx+siny=a cosx+cosy=a 求sinx+cosx=?

证明sinx+cos(x+y)siny/cosx-sin(x+y)siny=tan(x+y) 若sinx+siny=a,cosx+cosy=a(a≠0),则sinx+cosx=? 若a≠0 sinx+siny=a cosx+cosy=a 则sinx+cosx= sinx+siny=a,cosx+cosy=a,求sinx+cosx（a不等于0）. sinx+siny=a cosx+cosy=a 求sinx+cosx=? 高一数学已知sinx+cosy=a,cosx+siny=a则sinx+cosx为 若a不等于0,且sinx+siny+a,cosx+cosy=阿尔法,则sinx+cosx= 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=2sin[(a+b)/2]cos[(a-b)/2]sinx-siny=cosx+cosy=cosx-cosy=sinxcosy=cosxsiny=cosxcosy=sinxsiny= 已知sinx+siny=2/3,求2/3+siny-cos²a取值范围 已知sinx+siny=2/3,求2/3+siny-cos²a取值范围 cosx+cosy=1/2,sinx-siny=1/3,则cos(x+y)=? 已知cosx+cosy=1/2,sinx-siny=1/3,则cos(x+y)= 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=4/1,sinx-siny=3/1求cos(x-y) sinx+siny=2/5,cosx+cosy=6/5,求cos(2x-2y) 已知sinx+siny=0.4,cosx+cosy=1.2,求cos(x-y)