In a circle, two chords AB and CD are equidistant from the centre O. The length of AB is (3x−4)cm and the length of CD is (x+8)cm. A third chord EF is equal in length to CD and subtends a central angle of (2y+20)∘. The chord AB subtends a central angle of 100∘.
(i) Form two algebraic equations in x and y using the given information.
(ii) Solve the equations to find the values of x and y.
(iii) Determine the common length of the three chords and the angle subtended by chord EF at any point on the circumference of the circle.