Stage: 4 Challenge Level: 
Four circles of diameter 1 unit fit easily enough in a square of side 2 , but what is the smallest square into which we can fit 3 circles of diameter 1 unit?
Mixed trig ratios. Inequality/inequalities. Number theory. Manipulating algebraic expressions/formulae. Squares. Pythagoras' theorem. Right angled triangles. Stage 5 - Reviewed 2012. Mathematical reasoning & proof. Radius (radii) & diameters.
Published February 2004.
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