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Product Introduction
A4 paper size is an international standard of A series paper size defined by ISO216 as defined by ISO.
The aspect ratio of the A series paper size is 1: square 2 (1 than the root sign 2), that is, the "silver ratio", and then rounded to get an integer in millimeters.
The size of A4 copy paper and A4 printing paper most commonly used in our daily work is 210mm multiplied by 297mm, which translates into centimeters: 21cm × 29.7cm (21cm × 29.7cm).
A4 paper is the origin of 210mm × 297mm
Reason 1:
A rectangle with a length of 2 and a width of X, whose length and width are X and 1 respectively after folding in half, is required to be 1:X=X:2 in order to ensure similarity.
The proportion you get is.
However, 297 divided by 210, you get 1.414, which is close to, and this ratio is similar to the original paper shape after a piece of paper is folded in half.
If it were not for such a ratio, such as 4RV 3, then we would find that after folding in half, the shape of the paper would be distorted and changed to 3:2.
Reason 2:
In fact, to meet this ratio, there can be other values, such as 282mm × 200mm, or other sizes.
However, the value of 210mm × 297mm is related to the 4 of A4, because the size of A0 paper is 841mm × 1189mm Magi A4 paper is the size of A0 paper folded four times.
So the size of A4 paper is 210mm × 297mm.