Eh, going back when I was learning proofs in high school…
A square was 4 equal length sides arranged in two sets of parallel lines with four 90° right angles.
Two sets of parallel lines are necessary to make a rectangle, and a square is just a rectangle with equal sides.
Proofs are all about working the way through each step to getting to a distinct shape defined by those smaller steps. All squares are rectangles, but not all rectangles are squares. Technically if in remembering correctly, rectangles are also trapezoids, just with 90° right angles.
Parallelograms, not trapezoids. Kind of. Maybe. Or maybe trapeziums.
See… some define trapezoid as specifically one set of parallel sides (originally trapezium). Some as no parallel sides (originally trapezoid) Those two were swapped by some asshole, and then swapped back in England but not in America.
Though most now just say a trapezoid (or trapezium in England) is at least one set of parallel sides, which makes parallelograms a type of trapezoid. Which does make a rectangle a type of trapezoid.
They call only one pair of parallel sides a proper trapezoid instead.
Eh, going back when I was learning proofs in high school…
A square was 4 equal length sides arranged in two sets of parallel lines with four 90° right angles.
Two sets of parallel lines are necessary to make a rectangle, and a square is just a rectangle with equal sides.
Proofs are all about working the way through each step to getting to a distinct shape defined by those smaller steps. All squares are rectangles, but not all rectangles are squares. Technically if in remembering correctly, rectangles are also trapezoids, just with 90° right angles.
Parallelograms, not trapezoids. Kind of. Maybe. Or maybe trapeziums.
See… some define trapezoid as specifically one set of parallel sides (originally trapezium). Some as no parallel sides (originally trapezoid) Those two were swapped by some asshole, and then swapped back in England but not in America.
Though most now just say a trapezoid (or trapezium in England) is at least one set of parallel sides, which makes parallelograms a type of trapezoid. Which does make a rectangle a type of trapezoid.
They call only one pair of parallel sides a proper trapezoid instead.
I totally forgot that parallelograms were a thing in all that. And I never even considered naming differences over time.