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Ad hoctagon

I HAVE eight rods. I can use three of them to make the sides of a right-angled triangle of area 10 square centimetres.

Alternatively, I can use all eight of them to make the sides of an octagon, all of whose angles are the same, and all of whose vertices lie on a circle.

What is the area of that octagon?

£15 will be awarded to the sender of the first correct answer opened on Wednesday 18 February. The Editor’s decision is final. Please send entries to Enigma 1528, New ÐÓ°ÉÔ­´´, Lacon House, 84 Theobald’s Road, London WC1X 8NS, or to enigma@newscientist.com (please include your postal address). The winner of Enigma 1522 is Richard Kennaway of Norwich, UK.

Answer to 1522 Real in the lead

Twente beat Sporting; Sporting has a final total of 9 points and Twente has a total of 5 points

Visit www.newscientist.com/topic/enigma for recent puzzles and worked solutions