please do it fast

- A parametric surface S is described by the vector equation r(u,v) = noose i+ nsinvj + oak, whereOSuSdandOSver. i) Show that S is a portion of a surface of revolution. Make a sketch and indicate the geometric meanings of the parameters a and v on the surface. ii) Compute the vector I\". x r\" in terms of u and 1:. iii) The area of S is E(65\\/6_5 1) where n is an integer. Compute the value of n