Enigma 34: Cornered
7 January 2013
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From New Scientist #1176, 11th October 1979 [link]
“The figure”, said Professor Mortis, “shows a straight rod XY of quite infinite rigidity and totally infinitesimal width which is too long to be pushed around the right-angled corner in the corridor. It came along arm A, and it has got stuck on its way round into arm B. Now if you measure the width of the arms in the figure and interpret them according to the scale so helpfully provided, you will know the exact width of each arm, won’t you? Both figures are an exact number of inches, right? Yes. And now you can tell me, can’t you, the length of the longest rod which will just go round the corner? It must of course be straight and rigid and widthless, and incidentally it is still so heavy that it has to be pushed along flat on the floor.”
“Ten foot five,” I said.
“Perfectly right,” said he.
You can’t measure the figure as I did, because the figure shown here is only a rough copy of the professor’s; but can you tell me the width in inches of the arms A and B?