In a circle with centre O, chords AB and CD are equal.
The angles subtended at the centre by these chords are
∠AOB=(4y−10)∘ and ∠COD=(3y+20)∘.
(i) Prove that arcs AB and CD are equal.
(ii) Using the result of part (i), form an equation in y and hence find the value of y.
(iii) Determine the common measure of arcs AB and CD.}],