Talk:List of trigonometric identities

message: By WP:SIZESPLIT  and Wikipedia:Article size pages above 60 kb size should be split 
List of trigonometric identities is about 71 kb so is in need of a split.
Also the list is ab bit hard to follow so lets have a discussion about how we reorganize this page and maybe if and how how we should split it.
My idea is to split it in two, one with let us call it the high school trigonometry and a second one with more advanced subjects.
Advanced subjects would for me include:
* List of trigonometric identities#Historical shorthands maybe better at a page historical trigonometric functions 
* List of trigonometric identities#Angle sum and difference identities matrix forms
** Sines and cosines of sums of infinitely many terms
** Tangents of sums
** Secants and cosecants of sums
* List of trigonometric identities#Multiple-angle formulae 
** Chebyshev polynomial
** Hermite's cotangent identity
and many more 
lets discuss before we edit that makes nobody happy. WillemienH (talk) 12:44, 25 February 2016 (UTC)
replies: text: I think the article is on a coherent single topic and so should not be split up. I don't think it's hard to navigate, since there's a table of contents. With  two separate articles, someone might have a hard time finding what they're looking for, if they go to the wrong article. Loraof (talk) 20:31, 5 June 2016 (UTC)
replies: text: I agree. I don't think splitting up is a good idea. The cited guidelines with the 60kb are more than a crude rule of thumb than an absolute figure. We have plenty of compilation and overview articles that are larger than 60kb and where splitting them up is simply not a good option. In fact many of our excellent articles are > 70kb.--Kmhkmh (talk) 20:53, 5 June 2016 (UTC)
replies: text: I don't know if splitting is needed but holy crap is this page difficult to read with the current format and organization.  — Preceding unsigned comment added by Bofum (talk • contribs) 04:44, 1 October 2018 (UTC)
thread_title:  If the article gets too long, how shall we reorganize or split it? 

message: There are a great many existing trigonometric identities.  However, this article cannot contain all of them and has space only for the more significant identities. Please do not insert identities that are not in common use and especially do not include a huge list of them.—Anita5192 (talk) 17:49, 17 November 2019 (UTC)
replies: text: I wholeheartedly agree and would go even further. There are many identities on this page that are not sourced or sourced to unreliable sources. The page seems to be a magnet for people who want to see "their" identities in print and needs to be pruned from time to time to weed these things out. I've also noticed some basic identities (that should be in the list) without citations, so a straightforward weeding would have to be done with care and is probably a job for more than one editor.--Bill Cherowitzo  (talk) 23:08, 17 November 2019 (UTC)
thread_title:  Significant identities 

message: This page, despite seeming to have no active content, utilizes 100% of the core the thread is running on. Google Crome Version 84.0.4147.105 (Official Build) (64-bit)  — Preceding unsigned comment added by 75.109.252.140 (talk) 17:11, 4 August 2020 (UTC)
thread_title:  CPU Usage 

message: User  created a new overview figure, and replaced () the original with the new version in the article:
File:Unit circle angles color.svg|right|(original)
File:Unit circle sine cosine.svg|right|(new)
Pending discussion and consensus, I have restored () the original diagram, as the new one seems entirely unreadable without clicking on it to open the full-size source. Comments welcome. - DVdm (talk) 17:35, 22 September 2021 (UTC)
replies: text: I created the new diagram because the original one contained far too many distractions (see chartjunk). A couple years ago I consulted this diagram because I was asked to memorize the values in a class. The three different text colors, varying font sizes, and varying text directions make the initial diagram very hard to read. I can enlarge the font size in the new SVG file if readers prefer that. Crossover1370 (talk | contribs) 18:11, 22 September 2021 (UTC)
replies: text: Good idea, you can create another version with different font and/or size and add to the galery here, so we can compare and try to agree. - DVdm (talk) 18:27, 22 September 2021 (UTC)
replies: text:  I don't see what distractions you are referring to, since both diagrams contain the exact same information. The only difference is the colors, which in my opinion make the original diagram more readable: multiples of π/6 are blue; those of π/4, red.—Anita5192 (talk) 18:33, 22 September 2021 (UTC)
replies: text:  Indeed. And those of π/2, black. That's exactly what I was thinking too. - DVdm (talk) 18:41, 22 September 2021 (UTC)
replies: text: Apart from the color, there are also the varying font sizes and the changing direction of text. It is far easier to read text that is upright than text that is rotated 30, 45, or even 60 degrees. I actually believe that the rotating text is the biggest issue with the readability of the original diagram. Crossover1370 (talk | contribs) 19:16, 22 September 2021 (UTC)

text:  Black text laid over a black line is very hard to read: see in the new image how the leg of the π in 4π/3 runs together with the line. Simplifying a figure does not necessarily improve it: the different colors and angles used in the old image enhance understanding, rather than take away from it. -Apocheir (talk) 20:34, 22 September 2021 (UTC)
replies: text: I am willing to increase the size of the transparent zone or even change the text in the latter image to blue to increase its readability. I am not a fan of excessive use of color such as in the first image. However, I stated earlier that the biggest problem with the old image is not the color but rather the changing text direction - how much of the text is rotated 30°, 45°, or even 60°. Such text is much harder to read than upright text. Crossover1370 (talk | contribs) 21:24, 22 September 2021 (UTC)
replies: text: I don't have any problem reading the non-horizontal text. Indeed, years ago, in the days of manual drafting, we occasionally used non-horizontal dimensions to fit the diagram.—Anita5192 (talk) 02:37, 23 September 2021 (UTC)
replies: text: Sure, it is not hard to read the coordinates (I can clearly see that the coordinates at π/3 are (1/2, √/2)). But for students who are trying to memorize the diagram, the nearly-vertical text in some places makes the diagram as a whole harder to read (some may have to tilt their heads) and harder to memorize. Crossover1370 (talk | contribs) 03:41, 23 September 2021 (UTC)
replies: text:  I think that memorizing such diagrams is a not a good idea. In my experience, in order to recall access to a sin/cos-value, the only thing to memorize, was the trivial recipe to reproduce the table in List of trigonometric identities#A useful mnemonic for certain values of sines and cosines and to understand how to mirror things to the other quadrants . - DVdm (talk) 08:33, 23 September 2021 (UTC)
thread_title:  Overview figure 

message: In connection with Product-to-sum and sum-to-product identities,how about adding this article:https://wikimedia.org/api/rest_v1/media/math/render/svg/2073f2b5e451b6da9a646016cd076041c565f6bb(from https://fr.wikipedia.org/wiki/Identit%C3%A9_trigonom%C3%A9trique)?
This is Tangent formura of it.And using Negative angle formula,I can show like this.
\tan\theta\pm\tan\varphi=\frac{\sin(\theta\pm \varphi)}{\cos\theta\cos\varphi}240D:1E:309:5F00:5A:9595:FDF:A1F7 (talk) 06:50, 11 December 2021 (UTC)
replies: text: I added it to the table. Danstronger (talk) 14:07, 11 December 2021 (UTC)
thread_title: new suggestion

message: I think \tan(\theta) = \frac{sin(\theta)}{\cos(\theta)} but I'm not sure, since it's not listed on Wikipedia. John Moser (talk) 23:43, 29 January 2022 (UTC)
thread_title:  Incomplete list misses trivial identities