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MathNet 2007-part-01 — 187 problems (EN–VI) Question 88

Math Olympiad Vault · MathNet 2007-part-01 — 187 problems (EN–VI)

Question 88

A circle is called *good colored* if the vertices of any equilateral triangle inscribed in this circle are colored in distinct colors. Let $k$ be a circle with radius $2$.

a) Is there a coloring of the points on $k$ and inside $k$ in three colors such that $k$ and any circle with radius at least $1$ that touches $k$ are good colored?

b) Is there such a coloring in seven colors?