Do you remember the story of the Three Little Pigs? The Big Bad Wolf had no problem blowing down the houses of two of the pigs. One of the pigs, however, had a sturdy house. Carpenters use a unique rule to make sure that the rooms of your house are well built.
The Math Connection
In order to make sure that the corner of a room is square, builders need to create a 90-degree angle in the corner. How can they do this? They use a special calculation, called the 3-4-5 rule. This rule reminds them to measure three feet from the corner in one direction and four feet from the corner in the other direction. Next, the builder measures the distance between the two marks. The distance equals five if the corner is square. Have you guessed how it works?
See for yourself: http://woodworking.about.com/od/gettingstarted/qt/345Rule.htm
Watch the following video to learn more about the 3-4-5 rule.