Transform the integral to polar coordinates and compute its value, if possib

$($i$){\displaystyle \underset{0}{\overset{a}{}}}[{\displaystyle \underset{0}{\overset{\sqrt[\phantom{2}]{a^2-y^2}}{}}}(x^2+y^2)dx]dy$

$($ii$){\displaystyle \underset{0}{\overset{1}{}}}[{\displaystyle \underset{0}{\overset{x^2}{}}}f(x,y)dy]dx$