Two circles of radii 3.5 and 4.2 cm with centres O1 and O2 intersect at points A and B as shown. The distance between the two centres is 6 cm. Calculate: (a) The size of angle AO1B. (b) The size of angle AO2B. (c) The area of quadrilateral O1AO2B. (d) The shaded area.

Step 1: Identify the given information from the problem. Radius of circle with centre O_1 is r_1 = O_1A = O_1B = 3.5 cm. Radius of circle with centre O_2 is r_2 = O_2A = O_2B = 4.2 cm. Distance between centres O_1O_2 = 6 cm. Points A and B are the intersection points of the two circles. a) The size of AO_1B (to the nearest degree) Consider the triangle AO_1O_2. The sides are O_1A = 3.5 cm, $O_