解:(1)正方形A1B1C1D1如图D-19-19所示,显然A1B1=B1C1=C1D1=D1A1=2×2=4,所以S正方形=A1B=42=16.
(2)长方形A2B2C2D2如图D-19-19所示,显然A2B2=C2D2=2,B2C2=A2D2=4,所以S长方形A2B2C2D2=A2B2・B2C2=2×4=8.