Left diagram, mark diagonal and centre line. Right diagram, fold bottom edge to centre line and mark at M, this gives an approximate one fifth point.
FUJIMOTO'S METHOD OF ESTIMATING A FIFTH AND TWO SEVENTHS OF A SQUARE
The methods below depend on the fact that the ratio of the
diagonal of a square to
its side is within about one percent of the ratio of 7 to 5. For many
purposes this may
accurate enough, otherwise the methods give an excellent starting
point for Fujimoto's
convergent methods. In practice only marks are needed in any fold.
Estimating one fifth.
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Left diagram, mark diagonal and centre line. Right diagram, fold bottom edge to centre line and mark at M, this gives an approximate one fifth point. |
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Left diagram. Mark both diagonals. Right diagram. Put bottom edge along diagonal and mark S. This gives two sevenths up the diagonal (approx). |
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