Solution:
Let be the dimensions , so
The surface area
is zero is and
Hence is minimum when = 3. So the dimensions are
A covered box of volume 72 and the base sides in a ratio of 1:2 is to be made. The length of all sides so that the total surface area is the least possible is
Let be the dimensions , so
The surface area
is zero is and
Hence is minimum when = 3. So the dimensions are