Stage: 3 Challenge Level: 
If the sides of the triangle in the diagram are 3, 4 and 5, what is the area of the shaded square?
Diagram not to scale
smartphone. Manipulating algebraic expressions/formulae. Mathematical reasoning & proof. Generalising. Creating expressions/formulae. Ratio. Similarity. Other equations. Visualising. Right angled triangles.
Published June 1999.
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