[These pages were authored by the late Thoki Yenn, and were restored here from the Internet Archive by Erik Demaine, with contributions of missing files from various readers (notably Tommy Stevens, Roberto Morassi, and Boaz Shuval). If you spot any other bugs like missing images or pages, please report them.]

A-Format page one

 More about The A-Format & Silver Rectangle - page 1.
 If we have a square, each of the sides of which measures 1 unit in length, the diagonal of that square measures ]/2. In Fig. 376 we see the said square. The diagonal is AB. The diagonal is laid out along the base- line to AC, permitting us to construct rectangle ACDE. The long side is AC, the short side is AE. This rectangle has thus the proportions of the A-format. But we do not see the sacred cut until we enlarge the diagram by constructing the small square's double-size version. We see this in Fig. 377 in which the arc CB is extended to point F, after which the double-size version can be entered. We see that line ED is the upper horizontal sacred cut in square FGCA. The A-format is not one particular size. It is a ratio, represented by five basic sizes, each twice (or half) the size of its neighbour.
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