In a circle with centre O, chord AB subtends ∠AOB=60∘. Another chord CD is equal in length to AB.
a. (i) Find the measure of ∠COD.
b. (ii) A point P lies on the circumference in the minor segment cut off by chord CD. Determine ∠CPD.
c. (iii) A point Q lies on the circumference in the major segment cut off by chord AB. Calculate ∠AQB. Give reasons in each case.