As shown in the figure, in square ABCD, e and F are on BC and CD, respectively, ∠ EAF = 45 ° to prove s △ AEF = s △ Abe + s △ ADF

As shown in the figure, in square ABCD, e and F are on BC and CD, respectively, ∠ EAF = 45 ° to prove s △ AEF = s △ Abe + s △ ADF

It is proved that: extend CD to m, make DM = be, connect am, ∵ quadrilateral ABCD is square, ∵ ad = AB, ∵ B = ≌ bad = ≌ ADC = ADM = 90 °, ∵ in △ Abe and △ ADM, ab = ad ≌ B = ≌ admbe = DM ≌ Abe ≌ ADM (SAS), ≂ am = AE, s △ Abe = s △ ADM, ≂ mad = ≌ EAB, ≂ B