$($d$)f(x,y)=\{\begin{array}{ccc}\frac{xy}{x^{2}xy{y}^2}& if(x,y)(0,& 0)\\ 0& if(x,y)=(0,& 0)\end{array}$

$($e$)f(x,y)=\frac{sin(x^2{y}^2)}{x^2{y}^2}$

Find the subset of the domain in which the function is continuous