In a circle with centre O, three points A, B and C lie on the circumference such that ∠AOB=100∘, ∠AOC=60∘ and ∠BOC=140∘.
(i) Prove that chord AB is longer than chord AC.
(ii) Prove that chord BC is longer than chord AC.
(iii) Arrange the three chords AB, BC and AC in descending order of their lengths, supplying clear reasons for each step of your arrangement.