A circle has centre O. Chords AB and CD of the circle are equal.
(i) State the theorem that relates equal chords to the angles they subtend at the centre of a circle.
(ii) Using the theorem stated in part (i), explain why the arcs AB⌢ and CD⌢ must be equal in measure.
(iii) If ∠AOB=72∘, determine the measure of ∠COD. Give reasons for each step of your working.