Talk:Subtended angle/Archive 1

Subtend and insist
As far as I know, an angle is subtended by an arc, and not vice versa. Also, an object is subtended by a solid angle, and not vice versa. English is not my mother tongue. However, in my language there exists a second verb, which is used to express the opposite concept. I am not sure, but the most likely English translation of this verb is "to insist" (an angle insists on an arc = an angle defines the endpoints of an arc).

Thus, "subtended arc" is improper. The article should be called "subtended angle", and its text modified. Paolo.dL (talk) 17:20, 18 December 2007 (UTC)

Yes, this is very confusing. In the article listed as Solid Angle (http://en.wikipedia.org/wiki/Solid_angle), the following quote is made: "The solid angle, Ω, is the angle in three-dimensional space that an object subtends at a point." It appears there is confusion as to what subtend actually means. What should be the object of the verb? I must admit I see the statement that an object subtends an angle more frequently than visa versa. Should this article be corrected?Firth m (talk) 23:25, 24 February 2008 (UTC)


 * From a quick look at a few online dictionaries, it would seem to me that, in English at least, "subtend" appears to be a symmetric relation: if A subtends B, then B subtends A. The usage of a line/figure/object subtending a (solid) angle does seem to be somewhat more common, and is the only one given by MathWorld and thesaurus.maths.org, but the examples given in the general-purpose dictionaries strongly suggest that the opposite is linguistically valid as well.  Indeed, some of the examples given, such as an arc subtending a chord, don't (directly) involve angles at all.


 * Incidentally, it is somewhat notable that most of the Google results for "subtend" are indeed dictionaries of some sort. It's just not a very commonly used word.  —Ilmari Karonen (talk) 03:06, 3 November 2008 (UTC)


 * That's a lot of dictionaries. Let me add one more, the OED.  According to the OED, "subtend" comes from the Latin subtendere, which comes from "sub-" meaning under and "tendere" meaning "stretch".  As a transitive verb, it means "To stretch or extend under, or be opposite to: said esp. of a line or side of a figure opposite an angle; also, of a chord or angle opposite an arc." The sense of an angle subtending an arc goes back to the word's earliest use in English in Billingsley's 1570 translation of Euclid's Elements: "That angle is said to subtend a side of a triangle, which is placed directly opposite, and against that side." (I.IV.14)  In the opposite direction, that of an arc subtending an angle, the earliest use is Leonard Digges, A geometrical practise named Pantometria (1571), which says, "This done conioyne their endes togither and the angle subtended of the longest staffe is a right." (I.xviii)  So it seems that both "subtended angle" and "subtended arc", or equivalent constructions, have been used in English for over 450 years now. Ozob (talk) 15:28, 3 November 2008 (UTC)


 * It seems like Ozob's research is a bit more complete then mine. I just went to amazon and searched inside serveral geometry texts, but it does seem it is fine to use both constructions.  Thenub314 (talk) 19:04, 3 November 2008 (UTC)

Another proposal: the arc subtends the angle; the angle intercepts the arc. Michael Hardy (talk) 19:13, 3 November 2008 (UTC)


 * If it helps any, people should remember that "sub" (as a prefix) does not always mean "under" in Classical Latin.  It frequently means "coming up from below" (as in the verbs supporto, sustollo, and suffero).  216.99.198.254 (talk) 04:43, 21 June 2009 (UTC)


 * I think it is misleading to use dictionaries in this way.&ensp;Dictionaries reflect usage, whether that usage is strictly-speaking correct.&ensp;Also, this is part of a mathematics project, not English, so definitions and meaning could well be more specific.
 * Etymology is a much better method:&ensp;But a word is coined to represent a specific concept – Just because another concept could be represented by that same word does not mean that was the original intention.
 * Original usage, therefore, is a good indicator of original intent, but that was 440 years ago: What should the modern meaning be – informed by years of use and interpretation and (mis)understanding?
 * Most disciplines have their own jargon, which is usually more (and extremely rarely, if ever, less) specific than common usage.&ensp;And mathematics is surely the most disciplined of disciplines.
 * The most edifying observation is that MathWorld and thesaurus.maths.org only give one definition – a line subtends an angle.
 * So what do we want? – I want a word to describe one concept and have one meaning.&ensp;What is acceptable should, I feel, carry little weight.&ensp;We need a word that describes the construction of an angle from a line or similar, at a position, and 'subtend' fulfils that role admirably."The angle subtended by a chord at the major arc of a circle, is constant, and is π minus the angle subtended at the minor arc."We also need a word that describes the construction of an arc or line segment from an angle, although this would be less common in the practical sciences.&ensp;Insist (which I like, but I'd have to look-up) and intercept, have been proposed here, but I don't know if there is an established convention.&ensp;If I were writing about a line, I would probably use delineated, or segmented (as in a line-segment; but might be confused with the segment of a circle).&ensp;A line-segment could be defined by an angle (and a line).&ensp;An arc could be constrained by an angle.
 * We don't need to resort to overloading subtend.&ensp;I think we should actively avoid this, as the two links above have done.&emsp;Ζετα ζ (talk) 00:44, 3 July 2013 (UTC)