Height: h=8/a2

Materials used in this way are:

The range of a2+4XaXh=a2+32/a a is (a >；; 0)

That is, to find the minimum value of this function (S=a2+32/a), you can take the derivative first.

2a-32/a2=0

a3= 16

Then you can know the length, height and width.