The same string, when wound on the exterior four walls of a cube of side n cms, 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, in cms, is
Explanation:
If the cube is cut open as shown in the figure below, a rectangle with sides 4n and n is obtained.
The string is the diagonal along this rectangle, with length,
n2+(4n)2=n17
∴ The length of the string is n17.
Hence, option (b).
» Your doubt will be displayed only after approval.
Help us build a Free and Comprehensive Preparation portal for various competitive exams by providing us your valuable feedback about Apti4All and how it can be improved.