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MathNet 2015-part-05 — 191 problems (EN–VI) Question 169

Math Olympiad Vault · MathNet 2015-part-05 — 191 problems (EN–VI)

Question 169

The circles $\mathcal{K}_1$ and $\mathcal{K}_2$ in the figure are the circumcircle and incircle of the equilateral triangle $ABC$. A square $DEFG$ is inscribed in the circle $\mathcal{K}_2$ so that the point $D$ lies on the side $AB$. The circles $\mathcal{K}_3$ and $\mathcal{K}_4$ are of the same size and touch each other, each of them also touches two sides of the square $DEFG$. Determine the ratio of the radii of the circles $\mathcal{K}_1$ and $\mathcal{K}_4$.
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