Answer :

let the side of the square be x.
therefore, by pythagoras theorem,
[tex]x^{2}+ x^{2} = (42.3)^2 [/tex]
this implies that, [tex]2 x^{2} = 1789.29 x^{2} =894.645 x=29.91 (approx.) [/tex]
lipi
DIAGONAL=SQUARE ROOT OF 2*SIDE
42.3/1.41=SIDE=3.096CM
AREA=3.096*3.096
          =9.44CM