若cos(x+y)cos(x-y)=1/3,则cos^x-sin^y=?^为平方

Sin x-sin y=2/3 cos x-cos y=1/2 求cos(x-y) 证明COS（X+Y）COS（X-Y）=COS^2X-SIN^2Y Matlab编程问题 cos(x*y)*cos(x*(1-y))-0.5x*sin(x*y)*sin(x*(1-y))= y =(cos^2) x - sin (3^x),求y' y=sin根号1+x平方 y=cos平方(x平方+1)求导数 sin(x+y)sin(x-y)=k,求cos^2x-cos^2y 化简y=sin^2(x)+2sin(x)cos(x)+3cos^2(x) ) y=cos(x-y) sin(y+x)+根号3cos(x-y)为偶函数,tan(y)=__________ 函数y=sin平方x-sinxcosx+cos平方x的最大值为 设sin(x+y)sin(x-y)=m,则cos^2x-cos^2y的值 cos（x+y）=?sin（x+y）=?