## Calculus 8th Edition

Plot $II$
Let us set $v$ as constant, say $k$. $x=sinu$, $y=cosu sink$, $z=sink$ Let us name $sink$ as $a$ $x=sinu$, $y=acosu$, $z=a$ This is an ellipse parallel to $xy$ plane. Only Plot $II$ has such grid curves.