## Calculus 8th Edition

Plot $III$
Given : $x=cos^{3}u cos^{3}v$ $y=sin^{3}u cos^{3}v$ $z=sin^{3}v$ To find the grid curves corresponding to $u$ as constant , substitute $v=k$ $x=cos^{3}u cos^{3}k$ $y=sin^{3}u cos^{3}k$ $z=sin^{3}k$ This represents a family of astroid parallel to $xy$ plane with parameter $a=cos^{3}k$ Only Plot $III$ contains astroid as grid curves.