As appeared in PSLE 2010 exam:ADEF is rectangular cardboard with AF=7 cm. Two quarters circles have been cut from it as shown below. The remaining cardboard, which is the shaded part, has an area of 56 cm².Using π=22/7, find the length of BC.Diagram shows ADEF with A at the left hand corner and goes clockwise passing B and C and reaches D. AD is the length of ADEF. From D, it goes down to E and DE is the breadth. From E goes to F which is the length. From F goes up to A which is the breadth and is labelled as 7 cm. ABF and CDE are quarter circles (unshaded). The shaded area of the figure is BCEF.