Directions for questions 57 to 59: Answer the questions on the basis of the information given below.
Consider a cylinder of height h cm and radius

as shown in the figure (not drawn to scale). A string
of a certain length, when wound on its cylindrical surface, starting at point A and ending at point
B, gives a maximum of n turns (in other words, the strings length is the minimum length required to wind
n turns).
The same string, when wound on the exterior four walls of a cube of side n cm, starting at point C
and ending at point D, can give exactly one turn (see figure, not drawn to scale). The length of the
string is
