Problem: anup manages to draw 7 circles of equal radii with their centres on the diagonal of a square such that two extreme circles touch two sides of the square and each middle circle touches two circles on either side . find the ratio of radius of the circles to the side of the square . 
Options: ['a ) 1 : ( 2 + 6 ^ ( 1 / 2 ) )', 'b ) 1 : ( 4 + 7 ^ ( 1 / 3 ) )', 'c ) ( 2 + 7 ^ ( 1 / 2 ) ) : 1', 'd ) ( 2 + 7 ^ ( 1 / 2 ) ) : 2', 'e ) none of these']
e