It can be proved that ∠MAC=∠DBA, then ∠ AB=CA, ∠ Bad = ∠ ACM = 90, and ∠△ Abd△ CAM ∠ ADB =

∠M, AD = CM and then from cf = cf, ∠ mcf = ∠ DCF = 45, cm = ad = CD, it is proved that △ CDF △ CMF.

∠M= ∠CDF, so∠ ∠ADB=∠CDF.