Talk:Radian

From Wikipedia, the free encyclopedia

WikiProject Mathematics
Mathematics Portal
This article is within the scope of WikiProject Mathematics, which collaborates on articles related to mathematics.
Mathematics rating: Start Class High Priority  Field: Basics
One of the 500 most frequently viewed mathematics articles.
This article has been reviewed by the Version 1.0 Editorial Team.

Some talk has been archived in Talk:Radian/Dimensional analysis.

Contents

[edit] Mathematics and Physics?

What about other fields of science? Brianjd 09:57, 2004 Nov 16 (UTC)

Such as? --P3d0 14:31, Nov 16, 2004 (UTC)

[edit] Dimensional analysis

Some of the symbols in the 'dimensional analysis' section are not displaying properly in my browser. (I'm using Internet Explorer.) What is the problem? Thanks. Axl 18:01, 13 Jan 2005 (UTC)

Hmm, I'm only having this problem when I use a thin client; the display is fine with a desktop PC. Axl 21:22, 13 Jan 2005 (UTC)

go to preferances>rendering math and mess around with the setting untill something works. One of them WILL work.

I have moved jobs now and I no longer use a thin client. Thanks anyway. :-) Axl 20:13, 4 Mar 2005 (UTC)


Radians have units [L]/[L]. This matters when doing real dimensional analysis.Doolin 15:51, 2 May 2006 (UTC)

So add it. I would, but I have no idea what you mean by that, so I probably shouldn't. fel64 14:14, 3 June 2006 (UTC)

[edit] Trigonometric identities

According to the article, the use of radians makes the Limit of (sin x)/x as x approaces 0 equal to 1. However, this identity is true for any angle measurement unit. So why are radians used? --BrainInAVat 17:51, 1 October 2005 (UTC)

you are wrong, it's simply 1 only using radians... --Arirossa 09:46, 23 February 2007 (UTC)

Who invented the radian? And when?

[edit] SI Multiples

This seems out of place here. Is there any practicle use for them at all?

I have never seen or heard anyone mention milliradians or microradians, let alone stuff like megaradians. I would indeed propose to remove the table of SI multiples. MHD 12:18, 3 February 2006 (UTC)
I believe that milliradians are used in gunnery in some countries, since 1 mrad corresponds conveniently to 1 m at a range of 1000 m. I doubt that prefixes larger than milli- have ever been used. Indefatigable 17:17, 3 February 2006 (UTC)
Not so familiar with gunnery myself, glad someone else is. Can I assume from your message that you acknowledge the uselessness of the complete table of multiples? We could place a reference to milliradians as used in gunnery somewhere in the article, the rest of the table is not needed. I am quite curious if someone could provide an example of the use of kiloradians, megaradians or even gigaradians. That is how many times a complete circle? :-) MHD 20:03, 3 February 2006 (UTC)
A gigaradian is 5 \times 10^8 \over \pi complete circles. Or was that a rhetorical question? I think it's OK to delete or truncate the table. Several months ago, some folks merged all articles with prefixes into the base unit articles (kilometre merged into metre, gram merged into kilogram, and so on), and it was at this time that prefix tables were added into the articles on all SI base and derived units. For radians it does not make much sense. Indefatigable 21:51, 9 February 2006 (UTC)

They are used when considering a bead on a string which is being spun for example, rather than the distance it rotates( circumfrences) being measured the radius( string length) and the number of revolutions is. The number of revolutions is sometimes in radians (4π being 1 revolution) leading to measurements of something which rotates at say 3 million rad/s would be 3 Megarad/s. I dont really see an application of this out side of examination questions. Further, Radians is no longer considered SI is it? seing as it has no units it is now a derived unit as Indefatigable said.Wolfmankurd 18:17, 27 May 2006 (UTC)

I am involved in precision shooting in which milliradians feature heavily. I would like to query the accuracy of the statement a milliradian is equal to a metre at a range of 1000 metres. I believe that this is quite incorect. At 1000 metres a milliradian (according to my calculations) is equal to 90 centimetres which is more like one yard not one metre. Might seem like a small thing bt it is a maths topic so the maths should be right. —Preceding unsigned comment added by 203.171.86.27 (talk) 04:27, 24 October 2007 (UTC)

A radian is a length only if measured along a circle. If you want the length of one milliradian at 1000 meters, the only way it is meaningful mathematically is to measure off 1/1000th of the range along the circle centered at the shooter. That gives a height of 1000 sin .001, which is indistinguishable from 1 meter (it's off by a fraction of a micrometer). Zaslav 05:47, 29 October 2007 (UTC)

[edit] image size reduction

I managed to reduce the image size by a half, by using only 32 colors (I know there are only 5, but for some reason when using only 5 colors the computer chooses the wrong colors) http://xs100.xs.to/xs100/06185/Radian_cropped_color.png deal with this as you'd like.

pick the palet Wolfmankurd 18:01, 27 May 2006 (UTC)

[edit] FAC?

Surely it would not be too diffcult to polish this article to featured standard? Apart from some reference, what else is missing? -- ALoan (Talk) 16:25, 14 February 2007 (UTC)

It's a good article I agree, but doesn't have much content, although trying to include it all would make the article pages and pages long. Wolfmankurd 19:24, 23 February 2007 (UTC)

[edit] Angular velocity, angular frequency

It might be worth mentioning that angular velocities are often given in units of radians per second (rad/s or rad s-1). This is common in mechanical and electrical engineering. And a conversion factor to revolutions per minute would be useful.

In electrical engineering, physics etc, angular frequencies (symbol omega) are also measured in rad/s. The conversion factor to hertz (cycles per second) is 2 pi.

Someone else do this. All my edits seem to get deleted these days. I suppose that's something to do with having a dynamic IP address and not being bothered to log in.

84.9.82.184 08:45, 1 May 2007 (UTC)