What is the method used in construction when squaring a building?

The Pytagorean Theorum says that in a right triangle, the sum of the squares of the length of the 2 sides (adjacent to the right angle) is equal to the squre of the hypotenuse.

A simplified version of this for construction workers is based on the fact that this formulation comes out with nice even numbers when any multiple of the ratio 3:4:5 is used (9+16=25).

Thus if a building is say 44 feet long by 40 feet wide, the lay-out would begin on the straight 44' side. a measurement of 33' from one end of it "eyeball close" to perpendicular would be pulled and an arc swung maybe 3-5 feet long at that measurement.

Then from the opposite corner of the 44' wall, a 55' measurement would be pulled to intersect with the arc just drawn. A string pulled from the origin of the 33' measurement through this intersection and on out to the 40" point would square these 2 walls to each other well within 1/4" tolerance.

Lay-out people will just as readily say "Let's pull a 3:4:5" as they will "let's square it up"