已知cos(x-y)cosx+sin(x-y)sinx=3/5,则cosy的值为

已知Sin(x+y)Cosx-Cos(x-x)Sinx=3/5求tan2y的值 已知sin(x-y)cosx-cos(x-y)sinx=3/5求tan2y的值 化简sin(x+y)sinx+cos(x+y)cosx 化简sin(x+y)sinx+cos(x+y)cosx等于? 化简cos(x+y)sinx-sin(x+y)cosx 化简cos(x+y)sinx-sin(x+y)cosx sinx*sin(x+y)+cosx*cos(x+y)等于? cos（x+y）sinx-sin（x+y）cosx y= sin x cos x+sinx+cosx的值域 Y= SIN X - COS X / 2 COSX 的导数Y= SIN X - COS X / 2 COSX 的导数 cos(x+y)*cos(x-y)=cos*cosx+sin*siny cos(x+y)-cosx如何等于-2sin[(2x+y)/2]sin(y/2), 已知sinx+siny=1/3,cosx-cosy=1/5,求cos(x+y),sin(x-y).求过程! 已知cos(x-y)cosx+sin(x-y)sinx=3/5,则cosy的值为 已知sin(x-y)cosx-cos(x-y)sinx=五分之三求tan2y的值 已知y=tanx/cosx y=7/x的四次方 求导数y'=?y = tanx/cosx = sinx/cos²xdy/dx = cosx/cos²x - 2sinx(-sinx)/cos³x= 1/cosx + 2sin²x/cos³x= (cos²x + 2sin²x)/cos³x= (1 + sin²x)/cos³x这个解法中的 求函数y=cos(9/2π+x)+sin^2x的最大值和最小值还有一题 已知sinx+cosx=1/2,求sin^3x+cos^3x和sin^4x+cos^2x 证明sinx+cos(x+y)siny/cosx-sin(x+y)siny=tan(x+y)