已知Sin x+Sin y=1/2,Cos x+Cos y=根号3/3,求S

Sin x-sin y=2/3 cos x-cos y=1/2 求cos(x-y) y =(cos^2) x - sin (3^x),求y' 问道三角函数题已知sin(x)-sin(y)=-(2/3);cos(x)-cos(y)=(2/3);求cos(x-y) 已知函数y=sin(x/2)+根号3*cos（x/2),x属于R 已知函数y=4 cos²x+4倍根号3 sin x cos x-2,x∈R. 已知cos^2x-cos^2y=根号3/2,则sin(x+y）·sin(x-y)的值 sin^2x+cos^2y=1/2 求3sin^2x+sin^2y的最值 sin(x+y)sin(x-y)=k,求cos^2x-cos^2y 求y=cos²x+2根号3sinxcosx-sin²x的最大值、最小值. 化简y=sin^2(x)+2sin(x)cos(x)+3cos^2(x) 已知sin X+cos X=m,|m|小于等于根号2且|m|不等于1,求sin X^3+cos X^3,sin X^4+ 已知x-y=派/3,且sin x-siny=1/2,求cos(x+y).