In △ABC, point D lies on side BC and point E lies on side AC such that ∠BAD=∠BED.
a. (i) Show that points A, B, D and E lie on a circle.
b. (ii) If ∠ABC=72∘ and ∠ADB=40∘, calculate ∠AEB.
c. (iii) Using the same data, determine ∠ADE. Give reasons for each step.