The diagram shows a circle, centre \(O\), radius \(10\text{ cm}\). The points \(A\), \(B\), \(C\), and \(D\) lie on the circumference of the circle such that \(AB\) is parallel to \(DC\). The length of the minor arc \(AB\) is \(14.8\text{ cm}\). The area of the minor sector \(ODC\) is \(21.8\text{ cm}^2\).

(i) Write down, in radians, angle \(AOB\).

(ii) Find, in radians, angle \(DOC\).

(iii) Find the perimeter of the shaded region.

(iv) Find the area of the shaded region.