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Polycircles

Show that for any triangle it is always possible to construct 3 touching circles with centres at the vertices. Is it possible to construct touching circles centred at the vertices of any polygon?

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Pentagon

Find the vertices of a pentagon given the midpoints of its sides.

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Nim

Start with any number of counters in any number of piles. 2 players take it in turns to remove any number of counters from a single pile. The loser is the player who takes the last counter.

Attractive Tablecloths

Stage: 4 Challenge Level: Challenge Level:1


How many extra colours do you need to add to the $7$ by $7$ pattern to make the $9$ by $9$ pattern for each type of symmetry?

Where do those extra colours go?

How many extra colours would you need for the $11$ by $11$ design?

Where do those extra colours go?