z=Intan(x/y)
∂z/∂x=[tan(x/y)]'/tan(x/y)= (1/y)[sec²(x/y)]/tan(x/y)
= (1/y)/[cos(x/y)sin(x/y)=(2/y)/sin(2x/y)=(2/y)csc(2x/y)
∂z/∂y=[tan(x/y)]'/tan(x/y)= (-x/y^2)[sec²(x/y)]/tan(x/y)
= (-x/y^2)/[cos(x/y)sin(x/y)=(-2x/y^2)/sin(2x/y)=(-2x/y^2)csc(2x/y)
求z=Intan(x/y)的偏导数的过程