From BC =AC, ∴BD=AF( 1)
From ∠ c = ∠ ade = 60,
∴∠BDE+∠ADC= 120，
∠CAD+∠ADC= 120，
∴∠BDE=∠CAD(2)
∠DBE=∠AFD= 120 (3)
According to the conditions (1), (2) and (3)
△DBE?△AFD(A，S，A)
∴BE=DF=CD，
∴AB=BC=BD+CD。
Complete the certificate.