(1), as shown in the figure, the vertical line passing through point B is that GC intersects the extension line of GC at point H, and the intersection point D is DI⊥CE.

Because the squares of ABCD are BC=CD and BCD = 90,

In the square CEFG, there are CE=CG, ∠ ECG = ∠ ech = 90,

So ∠ BCH+∠ DCE = ∠ DCE = 90, that is ∠BCH=∠DCE.

△ BCH △ DCI (AAS) because BH⊥GH and DI⊥CE.

There is BH=DI, so S△CDE=CE×DI÷2=CG×BH÷2=S△BCG.

(2) As shown: