(2003? Ningbo) as shown in the figure, in the octagonal ABCDEFGH, ∠ A = ∠ B = ∠ C = ∠ D = ∠ E = ∠ F = ∠ G = ∠ H =135, AB.

Solution: If AB and DC intersect at point M, CD and FE intersect at point N, EF and HG intersect at point P, and GH and BA intersect at point Q, then MNPQ is a rectangle, and △BCM, △ Deng, △FGP and △AHQ are isosceles right triangles. The area of this octagon is equal to = the area of a rectangle-the area of four small triangles = 3.

So choose a.