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A Rope, Two Telephone Poles... and Some Confounding Math

The Puzzler


RAY: The question is, what must the distance be between the two poles so that the lowest point of this catenary is 25 feet above the ground?

If you made the mistake that I made and you drew the picture, and then went immediately and started to look up what the equation for a catenary was, you weren't going to get the answer.

But if you thought about it for a little longer you would realize that, it's impossible for that rope to get down to 25 feet above the ground, unless the two poles are touching each other.

TOM: I'll bet you all the little nerds went right to their graphing calculators. What a dirty trick!

RAY: I'm sorry. It was a dirty trick. It wasn't really a mathematical puzzler.

Do we have a winner?

TOM: The winner is Kirsten Gilbert from Winter Park, Florida.

[ Car Talk Puzzler ]

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