19. Estimate area of the shaded region

In the given figure, \(AB\) and \(CD\) are two diameters of a circle (with centre \(O\)) perpendicular to each other and \(OD\) is the diameter of the smaller circle. If \(OA = 14\) \(cm\), determine the area of the shaded region.

 

 

The area of the shaded region \(cm^2\).