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

The Puzzler


RAY: The question was: 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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