If ΔABC and ΔDBC are on the same base BC, AB = DC and AC = DB (Fig. 6.21), then which of the following gives a congruence relationship?

(a) ΔABC ≅ ΔDBC
(b) ΔABC ≅ ΔCBD
(c) ΔABC ≅ ΔDCB
(d) ΔABC ≅ ΔABCD
By given conditions AB = DC, AC = DB and common side BC, so ΔABC ≅ ΔDCB.