Stage: 5 Challenge Level: 
Find lengths in terms of the radii of the two red semicircles.
Radius (radii) & diameters. epsilons. Circles. Inequality/inequalities. Manipulating algebraic expressions/formulae. Stage 5 - Reviewed 2012. Cosine rule. Mathematical reasoning & proof. Creating expressions/formulae. Making and proving conjectures.
Published November 1999.
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