In a quadrilateral ABCD, ∠ABC=90∘ and ∠ADC=90∘. It is given that AB=DC and BC=AD.
a. (i) Prove that △ABC≅△CDA.
b. (ii) Hence, show that ∠CAD=∠DAB.
c. (iii) What special name can be given to the line AC with respect to ∠A of the quadrilateral? Justify your answer.