The string of length n is wound on the exterior four walls of a cube of side 'a' cm starting at point C and ending at point D exactly above C, making 4 turns equally spaced. The side of the cube is ______.
(A) 
(B) 
(C) 
(D) 
Ans 1:
Class : Class 8
[C]
see there are 4 sides each divided into 4 parts
therefore total no. of divisions:- 4*4 = 16
considering each side as a and length for one side as l we have l^2 = a^2 + (a/16)^2
now you can find the length for all 4 sides.