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Either Side
Age 14 to 16
ShortChallenge Level 
Around the inside of the wire the result is another equilateral triangle:
Around the outside of the wire, the disc describes an arc of a circle as the disk rolls around each of the corners of the triangle:
This problem is taken from the UKMT Mathematical Challenges.
You can find more short problems, arranged by curriculum topic, in our short problems collection.
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