Question 840473
r = radius of the cross section

surface area is {{{2*pi*r^2+9*(2*pi*r)}}}, the 9 used because it's height, one of the dimensions of the tubular part of the cylinder.
Simplify or adjust the form of the expression:
{{{2*pi(r^2+9r)}}}
{{{highlight_green(2pi*r(r+9))}}} which might or might not be easier to use than the first form.


FINDING THE RADIUS r.
{{{9*pi*r^2=144}}}, from given and formula for volume of cylinder.
{{{r^2=144/(9*pi)}}}
{{{r=12/(3*pi)}}}
{{{highlight_green(r=4/pi)}}}


Surface Area, {{{2pi(4/pi)(4/pi+9)}}}
{{{8(4/pi+9)}}}
{{{highlight(32/pi+72)}}}