Let the side length be a.
Triangle dcf is equal to triangle bce.
Triangle deg is similar to triangle bce and triangle dcf.
Angle dge= angle dcf=90 degrees-triangle dbf is an isosceles triangle.
So bd=bf dg=gf
Because bd= root number 2a; Bc=a, so ce= root number 2-1a.
Triangle dge is similar to triangle bgf.
So ge: gf = DG: GB
Cross multiply dg squared = ge GB = 4-2 times the root number 2.
Pythagorean theorem 4*dg square (that is, df square) =dc square +cf square =4-2 times the root sign and 2 times A square.
1/4 = one square divided by two formulas.
That is, the square area is 0.25.