It is one of the first formulas you learn in Geometry.
And using this equation to square a foundation or a deck is one of the easiest things you can do to ensure that you end up with perfect right angles or SQUARE CORNERS.
Start in one corner.
To apply the rule, start at stake B and measure out 3 feet toward A. Mark the string.
Beginning again at stake B, measure out 4 feet toward C. Mark the string.
With a second pair of hands and starting at your 3-foot mark on string A, pull a tape measure to the 4-foot mark on string C.
This diagonal measurement should read exactly 5 feet. When working alone, put a stake on the outside of the string at the 3-foot mark on A and tie a string to the stake. Mark this string with a 5-foot measurement. Now, pull the string so that the 5-foot mark lands on your 4-foot mark on C.
If the distance between A and C doesn't measure 5 feet, then move A or B out or in until it does.
When the measurement between the two points (A & C) reads 5 feet, your layout is square!
My Geometry teacher (Mr. G.L. Dotson) back at WCSH would be proud...
Or not...
