> 4:3 isn't the shape of a piece of paper, 1:√2 is. US letter sized paper is 8.5 inches wide and 11 inches tall. 4/3 is 1.333.... 11/8.5 is about 1.29. It's

> 4:3 isn't the shape of a piece of paper, 1:√2 is. US letter sized paper is 8.5 inches wide and 11 inches tall. 4/3 is 1.333.... 11/8.5 is about 1.29. It's not 4:3 exactly, but it's pretty close. A4 and friends are of course not 4:3--and aren't arbitrarily sized.