Originally Posted by
maviskw
A square is a rectangle with all sides the same length. Simple explanation. I married a math PhD and learned a lot of things that make life easier to understand.
Yes, I remember basic geometry more or less. And the label "Recs" sounds like it refers to a rectangle, but my question referred to the ruler, of course. I can see that if you sewed mirror images of pieces cut all the way around a recs ruler you would get a rectangle and not a square. I can see that the side opposite the right angle is not a 45º angle and thus makes the rectangle. Maybe that is the derivation of the term and the reason for the ruler's name.