Stage: 4 Challenge Level: 
This shape, which is constructed using four semi-circles, is called a Salinon. What is the relationship between the area of the shaded region and the area of the circle on $AB$ as diameter?
Inequality/inequalities. Manipulating algebraic expressions/formulae. smartphone. Circles. Generalising. Mathematical reasoning & proof. Number theory. Area. Radius (radii) & diameters. Stage 5 - Reviewed 2012.
Published October 2004.
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