It is known as ab = AC, ad = AE, BD = CE
prove:
∵AB=AC,AD=AE,BD=CE
∴△ABD≌△ACE(SSS)
∴∠BAD=∠CAE
∴∠BAD-∠CAD=∠CAE-∠CAD
That is, BAC = DAE
Known: as shown in the figure, ad = AE, ab = AC, ∠ DAE = ∠ BAC
It is proved that: in ∵ bad and △ CAE, ad = AE, bad = caeab = AC, bad = SAS and BD = EC
Known: as shown in the figure, ab = AC, ad = AE, ∠ BAC = ∠ DAE, verification: BD = CE
It is proved that: in ∵ bad and △ CAE, ad = AE, bad = caeab = AC, bad = SAS and BD = EC