Talk:Rhomboid

Question

rhomboids are like an rectangle eccept it cruquet

Yes, a squashed rectangle or a stretched rhombus would be good informal descriptions. Dbfirs 18:37, 17 July 2009 (UTC)[reply]

Isn't the word 'oblique' missing in a description of the angles incorporated in a rhomboidal structure? -- LenGarden — Preceding unsigned comment added by LenGarden (talk • contribs) 19:13, 27 August 2017 (UTC)[reply]

Yes, the article used to use the word oblique, but someone changed it to "non-right-angled". I was going to change it back, but we have no clear article on oblique angle (the definition is hidden in the middle of another article), and the term is not universally used, so I decided to leave it for clarity. Dbfirs 07:12, 28 August 2017 (UTC)[reply]

symmetries of rhomboid

rhomboid has no symmetry lines but it is regular —Preceding unsigned comment added by Yukinurfuad (talk • contribs) 14:33, 24 January 2010 (UTC)[reply]

Not regular in the technical sense because all angles are not equal, but it has rotational symmetry of order 2. I'll add these facts. Thank you. Dbfirs 20:26, 24 January 2010 (UTC)[reply]

The solid shape

"The term rhomboid is now more often used for a parallelepiped, a solid figure with six faces in which each face is a parallelogram and pairs of opposite faces lie in parallel planes."

Are you sure this is right? I'd understood it to mean an equilateral parallelepiped, where each face is a rhombus. -- Smjg (talk) 22:00, 27 March 2010 (UTC)[reply]

Yes, I would prefer to use it for the equilateral solid (squashed cube), but I suspect that, like trapezoid, the word is used differently in different contexts. The OED has the usage from 1800: "Phosphate of Soda... Its most common form is that of a lengthened rhomboid, the faces of which are inclined towards each other". The crystals of Sodium triphosphate, however, seem to be squashed cubes, so I am confused. Dbfirs 22:33, 27 March 2010 (UTC)[reply]

   "The term rhomboid is now more often used for a parallelepiped, a solid figure with six faces in which each face is a parallelogram and pairs of opposite faces lie in parallel planes."

Are you sure this is right?

I questioned that too. It's the sort of word that - in my experience - people don't use unless they know what it means. I also question some other statements. In my opinion, a square is a special case of the more general rectangle, and a rectangle a more general case of a rhombus, etc. Being the special case does not exclude the general term from applying, e.g. a swan is a bird, but not all birds are swans. In the same way, all squares are rhombi - I assume that is the plural, like radius and radii, annulus and annuli - and all rhombi are rhomboids. — Preceding unsigned comment added by Crysta1c1ear (talk • contribs) 17:39, 11 March 2012 (UTC)[reply]

In plane geometry, the term is non-standard because it does not fit in with the inclusive hierarchy. Rhomboids are a subset of parallelograms, but rhomboids and rhombuses are disjoint sets. (The Anglicised form is my preferred plural, but both plurals have been used for hundreds of years) This is like the term oblong which is a non-square rectangle, so oblongs and squares form disjoint subsets of rectangles. The terms oblong and rhomboid are not used in modern mathematics, but Robert Boyle used "Rhomboeides" to mean parallelograms with unequal sides in 1672. I've made a minor adjustment to the article because there seem to be two 3-D meanings. Dbfirs 07:35, 28 August 2017 (UTC)[reply]

Standard parallelogram

In many lessons as children, we were told this shape is called a "parallelogram", and later on learned that "parallelogram" applies to a category of shapes. Could a rhomboid be called a standard parallelogram or maybe a classic parallelogram? 72.72.203.2 (talk) 19:42, 15 March 2024 (UTC)[reply]