Let the side of the square be x. Then, its diagonal `= sqrt(2) x.` :. Radius of incircle` = x/2` & radius of circumcircle `= sqrt(2x)/2 = x/sqrt(2)` :. Required ratio `= ((π x^2)/4 : (π x^2)/2)` `= 1/4 : 1/2` `= 1 : 2`.