解：∵?$DE$?垂直平分?$AC，$?∴點?$A、$?點?$C$?關(guān)于?$DE$?對稱
∴?$AD = CD，$??$EC = EA$?
∵?$\triangle BCE$?的周長為?$13，$?∴?$BE + EC + BC = 13$?
∴?$BE + AE + BC = 13，$?即?$AB + BC = 13$?
∵?$\triangle ABC$?的周長為?$19，$?∴?$AB + BC + AC = 19$?
∴?$AC = 6$?
∵?$AD = CD，$?∴?$AD = 3$?
