Stage: 3 Challenge Level: 
At the corner of the cube, vertex A, circular arcs are drawn as shown. What fraction of the surface area of the cube is shaded? Try working out the answer without recourse to pencil and paper.
Short problems. Visualising. smartphone. Surface and surface area. Calculating with fractions. Pythagoras' theorem. Area. Fractions. Creating expressions/formulae. Circles.
Published May 2000.
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