Let
be the sides of the square ends and
be the length of the package.
Total area of the solid
.
Find
in terms of
.
Volume of the two hemispheres = Volume of one sphere.
\Formula for the volume of the sphere
.
Formula for the volume of the cylinder
.
Total volume of the solid
.
.

Solve for
.


.
Substitute
in
.


.
.
Differentiate on each side with respect to
.

Find the critical numbers by equating derivative to zero.
\





.



is minimum when
.
The radius of the cylinder that produces the minimum surface area is
.
.