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Circle Scaling
Age 14 to 16
Challenge Level 
If the areas are in the ratio 1:2:3 what can you say about the ratio of the radii?
Can you find some key right-angled triangles that will give you the lengths you are after? Pythagoras' theorem is useful!
Some useful constructions can be found in the Thesaurus if you look up "construction". A perpendicular line might be particularly useful.
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