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### Walking Around the World

```
Date: 08/18/99 at 11:22:03
From: Billy
Subject: Geometry

A man walks around the world. How much farther does his head go than
his feet? It has to be the same, right? If you walk to the moon your
head will travel the same distance. Is this a trick question?
```

```
Date: 08/18/99 at 11:58:52
From: Doctor Peterson
Subject: Re: Geometry

Hi, Billy.

No, it's not a trick question, but you have to think carefully. If you
walk in a straight line, your head goes as far as your feet, but not
if you walk in a circle. Here's a man walking around the world:

.....O.....
.....    /|\    .....
...          |          ....
...            / \             ..
..           ***********           ..
.         ****     |     ****         .
.        **         |         **        .
.       **           |           **       .
.       *             |             *       .
.      *              |              *      .
.      *               |               *      .
.      *               +---------------*------.
.      *                       r       *   h  .
.      *                             *      .
.       *                           *       .
.       **                       **       .
.        **                   **        .
.         ****           ****         .
..           ***********           ..
...                            ..
...                     ....
.....           .....
...........

His feet walk around the circumference of a circle with radius r. His
head goes around a circle with radius r+h. See if you can figure out
how much farther that is!

- Doctor Peterson, The Math Forum
http://mathforum.org/dr.math/
```
Associated Topics:
Middle School Conic Sections/Circles
Middle School Geometry

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