$\displaystyle \left(ii\right)\ \ let\ {\phi{}}_1=x^2+y^2+z^2=9 \\[2ex] \displaystyle \nabla{}{\phi{}}_1=\ \ i\frac{\partial{}{\phi{}}_1}{\partial{}x}+j\frac{\partial{}{\phi{}}_1}{\partial{}y}+\frac{\partial{}{\phi{}}_1}{\partial{}z}\\[2ex] =2xi+2yj+2zk\ \\[2ex] \displaystyle At\ \left(2,-1,2\right), \\[2ex] \displaystyle \nabla{}{\phi{}}_1=4i-2j+4k\ \ \\[2ex] \displaystyle \ {\phi{}}_2=x^2+y^2-z=3\ \\[2ex] $

$ \displaystyle \nabla{}{\phi{}}_2=\ \ i\frac{\partial{}{\phi{}}_2}{\partial{}x}+j\frac{\partial{}{\phi{}}_2}{\partial{}y}+\frac{\partial{}{\phi{}}_2}{\partial{}z}=2xi+2yj-k \\[2ex] $

$\displaystyle At\ \left(2,-1,2\right), \\[2ex] \displaystyle \nabla{}{\phi{}}_1=4i-2j-k \\[2ex] $

$\displaystyle Angle\ \theta{}\ between\ the\ surfaces\ {\phi{}}_1\ and\ {\phi{}}_2\ is\ the\ angle\ between\ their\ normals, \\[2ex] $

$\displaystyle \cos{\theta{}}=\frac{\left(4i-2j+4k\right).\left(4i-2j-k\right)}{\left\vert{}4i-2j+4k\right\vert{}\times{}\left\vert{}4i-2j-k\right\vert{}}\\[2ex]\cos \theta=\dfrac{16}{6\times{}\sqrt{21}}\\[2ex]\cos \theta=\dfrac{8}{3\ \sqrt{21}} \\[2ex] $