已知sin(x+y)/cos(x-y)=m/n,则tanx/tany=?

y=(sin x + COS x)^2 已知sinx=3/5,x∈(π/2,π),求【sin(x+y)+sin(x-y)】/【cos（x+y）+cos（x-y）】的值 y=2cos x (sin x+cos x) 已知函数f(x) =√3cos(2x-y)-sin(2x-y) (0 sin(x+y)sin(x-y)=k,求cos^2x-cos^2y 证明COS（X+Y）COS（X-Y）=COS^2X-SIN^2Y 证明cos(x+y)cos(x-y)= cos^2(x)-sin^2(y) 已知函数y=(sin x+ cos x)(sin x+cos x)+2cos x*cos x ,求它的递减区间语气亲和、态度友好 化简sin (x+y)sin x +cos (x+y)cos x= cosh (x + y)已知cos (x + y) = cos x cos y − sin x sin y求：cosh (x + y)再补充：求的是如何将cosh (x + y) 变成coshx cos hy - sin hx sin hy而不是证明cos h(x + y) = coshx cos hy - sin hx sin hy 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Sin x+Sin y=1/2,Cos x+Cos y=根号3/3,求S求Sin(x-y)/2 解微分方程：y` cos y =(1+cos x sin y)sin y. 已知sin(x+y)/cos(x-y)=m/n,则tanx/tany=? 已知cos(x-y/2)=-1/9,sin(x/2-y)=2/3,0 已知cos(x-y/2)=-1/9,sin(x/2-y)=2/3,0 已知sin(x-y)cosx-cos(x-y)sinx=3/5求tan2y的值 已知cos(x+y)cosy+sin(x+y)siny=4/5,求tanx的值