Wikipedia:Featured article review/Trigonometric functions/archive1

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The following is an archived discussion of a featured article review. Please do not modify it. Further comments should be made on the article's talk page or at Wikipedia talk:Featured article review). No further edits should be made to this page.

The article was removed by User:Marskell 17:40, 19 July 2008 [1].

Trigonometric functions[edit]

Review commentary[edit]

Notified: User talk:Stevenj, User talk:Jagged 85, User talk:Michael Hardy, User talk:Ricardo sandoval, Wikipedia talk:WikiProject Mathematics. --Ioannes Pragensis (talk) 12:44, 12 June 2008 (UTC)[reply]

An old FA, needs to be updated to the current standards:

  • 1a / 2b - better structured, no short paragraphs
  • 1b - more about the early history of the subject, more about applications
  • 1c - more inline references (history, proofs of mathematical properties)
  • 3 - partly duplicite images in the lead, more images in the body of text
  • some minor WP:MOS issues (formatting, white spaces in the article due to badly placed images etc.)

I hope that it will help to make the article better.--Ioannes Pragensis (talk) 12:30, 12 June 2008 (UTC)[reply]

Comment: I like the article, but it seems to need some work to remain FA. Some thoughts:

  • There is very little material on applications. I guess some example formulae where they show up would be good. The content of uses of trigonometry should be summarized here, too.
  • The preceding comment is actually an instance of a more general wish: I wish the article has more of a motivational section or flavor. What are sin, cos, cosec etc. good for?
  • "The set of zeroes of sine (i.e., the values of x for which sinx = 0) is {nπ, ...}" - this shows up in the "Right triangle definitions" part. It is not clear whether this is to be read as a definition of π Is it? If so, make this more clear. If not, this way of defining pi should be somewhere in this article, I think. In the same section, it should be mentioned somehow that tan is not defined (or defined to be infinity) if cos = 0. This may not be clear to a lay reader otherwise.
  • The fact, that every periodic function can be expressed by sin and cos deserves a more elaborate mention here, I feel. (This could go in an "Applications" section)
  • There are very little specific references. I'm convinced that every argument in the article is somewhere in the refs. But, historical claims should be backed up by a precise ref. Also things like "From a theorem in complex analysis, there is a unique analytic extension of this real function to the complex numbers." should be given a precise reference to a book (so that the reader can look up, which theorem it is).
  • The table "Trigonometric functions in the complex plane" needs a caption!
  • From a quick scan of the ref list, I see that there seems to be no "standard" math textbook covering the themes of complex series and so on. Please give on or two standard analysis books. References should be formatted with citation templates. Some of them are more external links than academic refs(?).
  • The "other useful properties" section contains only one property. Perhaps this should be merged somehow with the preceding sections. Jakob.scholbach (talk) 13:14, 12 June 2008 (UTC)[reply]

Comment: The pictures "Trigonometric functions in the complex plane" are not properly explained (where are the axes, what is the meaning of colors).--Ioannes Pragensis (talk) 16:54, 12 June 2008 (UTC)[reply]

Two out of four graphs of the sine, cosine, and tangent functions make no sense geometrically. The reason is that the scale is not right. If the variable is measured in radians, then the slope of sine and tangent at the origin should be 1. This is clearly not so in these drawings. Therefore it makes no sense to label the x-axis with fractions of pi, it could just as well have been degrees. The radian measure is defined in such a way as to make derivative at the origin 1. If it is not 1, these are not radians. Katzmik (talk) 08:08, 13 June 2008 (UTC)[reply]
Response to Katzmik The algebraic slope of these graphs (dy/dx) where they cross the x-axis is 1. The visible slope will only be 1 if the horizontal and vertical scales are equal. In these examples, the horizontal and vertical scales are not equal. This has no connection with the labelling of the axes. Most of the presentation in the article up to this point measures angles in radians, so it makes sense to label the x-axis on these graphs in radians too, for consistency. If you wish to re-draw the graphs so that they have equal horizontal and vertical scales, you will also have to re-arrange the layout of the whole section, as the aspect ratios of the graph images will change considerably. Gandalf61 (talk) 10:40, 13 June 2008 (UTC)[reply]
In my opinion, the scale should be the same in order for a first-time reader actually to derive benefit from the drawings. Katzmik (talk) 09:01, 15 June 2008 (UTC)[reply]


FARC commentary[edit]

Suggested FA criteria concerns are prose (1a), referencing (1c), structure (2), and images (3). Marskell (talk) 09:22, 4 July 2008 (UTC)[reply]
The above discussion is preserved as an archive. Please do not modify it. No further edits should be made to this page.
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