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.
sinx+siny=-1/3 cosx+cosy=1/2,求sin(x+y)的值.
已知sinx-siny=1/2,cosx-cosy=1/2,x、y均为锐角,求sin(x-y)
sinx+siny=2/5,cosx+cosy=6/5,求cos(2x-2y)
证明cosx(cosx-cosy)+sinx(sinx-siny)=2sin(x-y)/2
sinx+siny=1/2,cosx+cosy=(根号3)/3,求sin[(x-y)/2]
已知sinx+siny=(√2)/4,cosx+cosy=1/2,求cos(x-y)的值.
已知cosx+cosy=1/2,sinx-siny=1/3,求cos(x+y)
sinx+siny=√2/2,求cosx+cosy的取值范围
sinX+sinY=1 cosX+cosY=0 求cos(2X)+cos(2Y)的值
已知sinx+siny=1/2,cosx+cosy=1/3,求cos²((x-y)/2)
设cosX+cosY=1/2,sinX+sinY =1/4,求cos(X-Y)的值