Question
In figure, diagonal AC of a quadrilateral ABCD bisects the angles A and C. Prove that AB = AD and CB = CD.

Solution
In ∆ABC and ∆ADC,
∠BAC = ∠DAC | Given
∠ACB = ∠ACD | Given
AC = AC | Common
∴ ∆ABC ≅ ∆ADC | ASA Axiom
∴ AB = AD | C.P.C.T.
and CB = CD. | C.P.C.T.