The diagram shows the right-angled triangle \(OAB\). The point \(C\) lies on \(OB\). Angle \(OAB=\frac{\pi}{2}\) radians and angle \(AOB=\theta\) radians. \(AC\) is an arc of the circle, centre \(O\), radius \(12\) cm and \(AC\) has length \(9.6\) cm.

(i) Find the value of \(\theta\).

(ii) Find the area of the shaded region.