# M5.4.8

Solves real-world problems involving the

**Pythagorean relationship**.### Measuring the Earth

How to measure the Earth's diameter with a meter stick, a stopwatch, and some math.

### Square Roots Using a Carpenter's Square

As demonstrated in a PUMAS example from Lin H Chambers, "How Now, Pythagoras", master carpenters regularly make practical use of geometry and, at times, the Pythagorean theorem in their craft. I found this out some time ago when a good friend told me how an old-time carpenter he worked with calculated square roots using a carpenter's square.

### How Now, Pythagoras?

You may think of the Pythagorean theorem as useful only to geeky college freshmen who want to calculate how many steps they are saving by walking across the grass. Recently I learned of a very practical use of this theorem in a very unexpected place.