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Napoleon's Hat

Age 16 to 18
Challenge Level Yellow star
  • Problem
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Why do this problem?
Learners can investigate using the interactivity, make a conjecture and then try to prove their own conjecture.

It can be an exercise in coordinates.

It is useful for learners to appreciate that the symmetry of the result makes it unecessaryto work out all three distances.

Possible approach
Ideally learners would work independently on this problem.

Key question
How do we find the coordinates of the centroid of an equilateral triangle?

Possible support
GeoGebra is FREE educational mathematics software and your learners can experiment with it and draw their own dynamic diagrams.





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The NRICH Project aims to enrich the mathematical experiences of all learners. To support this aim, members of the NRICH team work in a wide range of capacities, including providing professional development for teachers wishing to embed rich mathematical tasks into everyday classroom practice.

NRICH is part of the family of activities in the Millennium Mathematics Project.

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