求:由方程所确定的隐函数的导数dy/dx?y=cos(x+y)

y = cos(x + y)
dy/dx = dcos(x + y)/d(x + y) · d(x + y)/dx,链式法则
dy/dx = - sin(x + y) · (1 + dy/dx)
dy/dx = - sin(x + y) - sin(x + y) · dy/dx
dy/dx · [1 + sin(x + y)] = - sin(x + y)
dy/dx = - sin(x + y)/[1 + sin(x + y)
dy/dx = - 1/[1 + csc(x + y)]

求:由方程y=cos(x+y)所确定的隐函数的导数dy/dx?
F(x，y)=y-cos(x+y)≡0；故dy/dx=-(∂F/∂x)/(∂F/∂y)=-sin(x+y)/[1+sin(x+y)]