Reason 1:
One rectangle, length is 2, width is X; after double it,the length is X and the width is 1, then in order to ensure similar as before, just rewuest 1:X=X:2. Got the ratio is . However 297 divide 210 is 1.414, close to . The ratio just is ratio of one sheet paper and before double up it. If not like this ratio, for example 4:3, then we can find the paper shape will be distortion, become to 3:2.
Reason 2:
There is other value of number meeting the ratio, like 282mm*200mm, or other size. But 210mm*297mm, the value of number related to 4 of A4, because A0 paper ‘s size is 841mm*1189mm, after A0 paper fold 4 times is A4 paper size.
So A4 paper size just is 210*297mm.
Oliver Tian
2015-7-11
Oliver@qdflying.com |
