[填空题]
A right cylinder has height hh mm an;qs* (zpuy totx47ha, d diameter xx mm. The volume of this cylcom)-g s5. a6p -jqqpcinder is equal ts6qq.- c opm-)agj5p co $45mm^3$.
The total surface area, A, of the cylinder can be expressed as $A = \frac{\pi}{2}x^2 + \frac{k}{x}$.
1.Find the value of k.k=
2.Find the value of x that makes the total surface area a minimum.x= mm
