$If$ curl vec$(F)=(x^2+z^2)vec(j)+2$vec$(k),$ find ${\displaystyle \underset{C}{\overset{\phantom{}}{}}}$vec$(F)*dvec(r),$ where $Cis$ a circle $of$ radius $3,$ centered $at$ the

origin, with

$(a)Cin$ the $xy-$plane, oriented counterclockwise when viewed from above.

${\displaystyle \underset{C}{\overset{\phantom{}}{}}}$vec$(F)*dvec(r)=$

$(b)Cin$ the $xz-$plane, oriented counterclockwise when viewed from the positive $y-$axis.

${\displaystyle \underset{C}{\overset{\phantom{}}{}}}$vec$(F)*dvec(r)=$