By considering △ ABC and △ ADC
We know that AC bisects at ∠ A
So we get
∠ BAC = ∠ DAC
We know that AC is common i.e. AC = AC
From the figure we know that AC bisects at ∠ C
∠ BCA = ∠ DCA
By ASA congruence criterion we get
△ ABC ≅ △ ADC
Therefore, it is proved that AB = AD and CB = CD (c. p. c. t)