Thursday, October 7, 2010

Area & Perimeter PSLE 2010 P2 Q10

10. ADEF is a rectangular cardboard with AF = 7 cm. Two quarter 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.












1/2  x  22/7  x  7  x  7  =  77

77  +  56  =  133

133/7  =  19

19  -  7  -  7 =  5 cm

It is 5 cm.
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  1. AnonymousJanuary 1, 2011 at 7:56 AM

    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.

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