How i solve the best solution of ncert class 10 areas related to circles please help me to solve the exercise 12.3 question number 9 . Find the easiest and simplest way to solve this question also find the best solution of this question. In Fig. 12.27, 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 = 7 cm, find the area of the shaded region.