In square ABCD, f is the midpoint of AD, BF and AC intersect at point G, what is the area ratio of triangle BGC to quadrilateral CGFD

In square ABCD, f is the midpoint of AD, BF and AC intersect at point G, what is the area ratio of triangle BGC to quadrilateral CGFD

Connecting DG, the quadrilateral is divided into two triangles, and △ CDG ≌ △ CBG, so the area of two triangles is equal, AF = DF = BC / 2, △ AFG