Question 751782
h=3d=3(2r)=6r


{{{
A[s]=2*pi*r^2+h(2*pi*r)
}}}




{{{
A[s]=2*pi*r^2+6r(2*pi*r)=14*pi*r^2
}}}


so that


{{{
126=14*pi*r^2
}}}

{{{
r=3/sqrt(pi))
}}}


:)