First, a disclaimer. This puzzle came from the Car Talk program on NPR, so listeners of that program are not allowed to give the answer!

You have two rather tall telephone poles, each 100 feet tall.

You have a 150 foot long rope strung between the tops of the two poles, and the poles are separated by a distance that allows the lowest point of the rope to be 25 feet above the ground.

How far apart are the two poles?

(Hint: the curve the rope makes is called a catenary.)

Be sure to show your work when you solve this...


tanstaafl.