# Foldable constant rectangle

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## Foldable Constant Rectangle

If you need a foldable rectangle then this is the foldable rectangle for you. A rectangle with these proportions maintains a constant aspect ratio when folded in half perpendicular to the long axis and rotated 90 degrees.

In reasonable parts of the world this is the ratio used for paper. For example, A4 paper.

## Notes

Foldable Constant Rectangle Aspect Ratio = SQRT(2) = 1.414213562373 Video screen Aspect Ratio = 4/3 = 1.333... (Example: 640/480=1.333...)

Given a width of 640 pixels,

``` Video screen height = 640 / (4/3) = 480
Foldable Constant Rectangle height = 640 / SQRT(2) = 452.54833995939
```

Difference in height is

``` (640 / (4/3)) - (640 / SQRT(2)) = 27.45166004061 or approximately 27 pixels
```

Another interesting constant, The Golden Ratio, φ.

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