As shown in the figure, in △ ABC, ∠ ABC = ∠ ACB, D is on the line BC, e is on the line AC, and ∠ ade = ∠ AED (1) explore the quantitative relationship between ∠ bad and ∠ CDE and explain the reason (2) If D is on the extension line of CB and E is on the extension line of AC, is the conclusion in (1) still valid

As shown in the figure, in △ ABC, ∠ ABC = ∠ ACB, D is on the line BC, e is on the line AC, and ∠ ade = ∠ AED (1) explore the quantitative relationship between ∠ bad and ∠ CDE and explain the reason (2) If D is on the extension line of CB and E is on the extension line of AC, is the conclusion in (1) still valid

1、
∵∠ ADC is the outer angle of △ abd
∴∠ADC＝∠ABC+∠BAD
∵∠ADC＝∠ADE+∠CDE
∴∠ABC+∠BAD＝∠ADE+∠CDE
∴∠ADE＝∠ABC+∠BAD-∠CDE
∵∠ AED is the outer angle of △ CDE
∴∠AED＝∠ACB+∠CDE
∵∠ADE＝∠AED
∴∠ABC+∠BAD-∠CDE＝∠ACB+∠CDE
∴2∠CDE＝∠ABC+∠BAD-∠ACB
∵∠ABC＝∠ACB
∴2∠CDE＝∠BAD
2. Establishment
∵∠ADE＝∠AED
∴∠DAC＝180-2∠ADE
∵∠ACB＝∠DAC+∠ADC
∴∠ACB＝180-2∠ADE+∠ADC＝180-∠ADE-（∠ADE-∠ADC）
∵∠ADE-∠ADC＝∠CDE
∴∠ACB＝180-∠ADE-∠CDE
∵∠ABC＝∠ACB
∴∠ABC＝180-∠ADE-∠CDE
∴∠BAD＝180-（∠ABC+∠ADC）
＝180-（180-∠ADE-∠CDE+∠ADC）
＝180-（180-2∠CDE）
＝2∠CDE