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Problem 388

Geometry Difficulty 2.0 Find the answer UKMT Junior Mathematical Challenge · United Kingdom · 2018

The perimeter of the regular decagon $P$ is 8 times the perimeter of the regular octagon $Q$ . Each edge of the regular octagon $Q$ is 10 cm long. How long is each edge of the regular decagon $P$ ? (A) $8\text{ cm}$ (B) $10\text{ cm}$ (C) $40\text{ cm}$ (D) $60\text{ cm}$ (E) $64\text{ cm}$

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