As shown in the figure, in △ ABC, ab = AC, D and E are on the sides of BC and AC respectively, and ∠ 1 = ∠ B, ad = de. verify: △ ADB ≌ △ Dec

As shown in the figure, in △ ABC, ab = AC, D and E are on the sides of BC and AC respectively, and ∠ 1 = ∠ B, ad = de. verify: △ ADB ≌ △ Dec

It is proved that ∵ B + ∵ bad = ∵ 1 + ∵ EDC, and ∵ B = ∵ 1, ∵ bad = ∵ EDC. AB = AC, ∵ B = ∵ c. AD = De, ≌ ADB ≌ △ Dec