Talk:Right angle

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Definition?

Please check the order of definition. Defining the right angle as 90° seems improper to me, as a degree is commonly described as 1/90 of a right angle, or 1/360 of a full rotation. If a full rotation is a basic notion, then the right angle would be more clearly derived from it than from a degree. It should be possibly noted also, what axiom states the full turn meaning, and the property 'all full turns are equal' so that we can derive 'all their quarters (ie. right angles) are equal'. --CiaPan 08:51, 2 November 2007 (UTC)[reply]

My Geometry textbook has a hole in the logic there, too. Z gin der 2008-05-24T19:44Z (UTC)

its seiys head —Preceding unsigned comment added by 92.7.142.253 (talk) 17:24, 6 April 2011 (UTC)[reply]

First, it is not improper to define a right angle as 90°; a quick search finds many reputable sources that do just that. It is also what many other language WP pages have used. Second, even if there is a chicken-and-egg problem re whether 90° can be used as a strict definition, it is entirely uncontroversial that an equivalency exists. Stating the 90° equivalency early on in the article is very helpful to many readers who are familiar with the language-agnostic measure "90°" but not with the English term "right angle". —WinTakeAll 💬 05:31, 26 April 2017 (UTC) 05:31, 26 April 2017 (UTC)[reply]

Saving some speedy-reverted content

Saving some speedy-reverted content. Maybe could be reworked/reintroduced into the article.

Arc with dot symbol

A Polish colleague of mine uses the circle with dot notation, but I have not found any non-polish people who use it. Anyone found an authoritative source for this symbol? Billlion (talk) 21:44, 23 August 2013 (UTC)[reply]

In Germany, as to my knowledge, the circle with dot notation is actually the only one that is used, at least in school education. I only got to know the square notation when reading English publications in university (I am German myself). While I do not have any particular "authoritative source" for this symbol, any German elementary geometry school book should suffice. --89.204.130.83 (talk) 12:09, 1 September 2013 (UTC)[reply]

@Billlion: Do Web pages count as a source? Try searching for "kąt prosty" or "trójkąt prostokątny" ('right angle' and 'right triangle', respectively, in Polish) in graphics. You can find, for example:

Right triangle at eszkola.pl ('e-school')
Acute, right and obtuse angle at eszkola.pl
Right triangle circumference at www.cauchy.pl (school-level math excercises)
Sides correlations in setsquares at math.us.edu.pl (Math Institute of University of Silesia in Katowice)
~~Types of angles at interklasa.pl (interclass)~~ – not active anymore. --CiaPan (talk) 08:17, 8 November 2023 (UTC)[reply]
~~Quadrilaterals characteristics at wielokat.pl (wielokąt = polygon)~~ – not active anymore. --CiaPan (talk) 11:21, 22 March 2024 (UTC)[reply]

They all use the symbol. However, none of them defines its meaning.
Best regards, CiaPan (talk) 06:21, 30 June 2017 (UTC)[reply]