As shown in the figure: ab = AE, BC = ed ∠ B = ∠ E. verify that ∠ C = ∠ D is a Pentagon, and the counter clockwise letter is ABCDE

As shown in the figure: ab = AE, BC = ed ∠ B = ∠ E. verify that ∠ C = ∠ D is a Pentagon, and the counter clockwise letter is ABCDE

Connect AC, ad,
AB=AE,
∠B=∠E,
BC=ED ,
△ABC≌△AED,[SAS]
∠ACB=∠ADE,
AC=AD,
∠ACD=∠ADC,
∠ACB+∠ACD=∠ADE+∠ADC,
∠BCD=∠EDC,(∠C=∠D)