Layout Squaring (3-4-5)

Formula and source

Diagonal = sqrt(a^2 + b^2) (Pythagoras / the 3-4-5 rule). For a rectangle the two diagonals are equal when square, so out-of-square = |d1 - d2| and the longer diagonal's corner is the one to draw in.

The Pythagorean 3-4-5 right-angle layout method (public) and the standard foundation- and deck-squaring technique.

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