https://www.explainxkcd.com/wiki/api.php?action=feedcontributions&user=162.158.222.123&feedformat=atomexplain xkcd - User contributions [en]2024-03-28T19:32:26ZUser contributionsMediaWiki 1.30.0https://www.explainxkcd.com/wiki/index.php?title=Talk:272:_Linux_User_at_Best_Buy&diff=225024Talk:272: Linux User at Best Buy2022-01-20T11:41:31Z<p>162.158.222.123: </p>
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<div>Not that Macs or Linux are invulnerable to malware. (Anyone else remember the {{w|Morris worm|Internet Worm}}, which would surely have ripped through Linux machines if not encountered on Unix, already, in pre-Linux days. Other exploits ''have'' been discovered, and had to be fixed.) Having said that, both types of machine ''tend'' to be safer from an OS security model point of view, from being a minority target that is largely overlooked ''and'' from the end-users being generally more savvy against liveware component attacks. However with the targetted growing flood of new users, that may well be changing. The latter two points, at least, although I'm sure ''some'' of the distros "boot as root" as well.<br />
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The speed of Linux also tends to be more from being more finely-honed by the last generation or two of geeks. Less clutter (at least with the distros ''I'' like, YMMV with some of the more "user friendly" ones) and the somewhat intimate knowledge of the system that the user tends to get and is able to act upon if anything displeases them (although, again, that may be changing). These days (and those days, I'm pretty sure) you ''can'' get mainstream AV programs for Linux (and Mac) and while I'm not going to say they're ''necessary'' for Linux, they're available and primed to help you out of various messes you ''could'' encounter. [[Special:Contributions/178.98.31.27|178.98.31.27]] 08:07, 20 June 2013 (UTC)<br />
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:Approximately 15 ago I did deactivate the firewall at my main (Linux) internet gateway for some tests only for a few minutes. I WILL NEVER DO THAT AGAIN! I only remember the root access was done by a user name r00t and my log files at "/var/log" had been deleted. When I did figure out that attack I immediately disconnected it from the internet, but I also had to do a complete new install to that system. Linux is only secure when you know how to secure it.--[[User:Dgbrt|Dgbrt]] ([[User talk:Dgbrt|talk]]) 22:01, 5 August 2013 (UTC)<br />
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Most linux virus scanners are to scan e-mails for windoze viruses. [[Special:Contributions/184.66.160.91|184.66.160.91]] 04:09, 27 August 2013 (UTC)<br />
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Is the motorbike backflip and speedaway a reference to something? [[Special:Contributions/141.101.98.133|141.101.98.133]] 14:03, 17 August 2016 (UTC)<br />
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What Linux distros do you guys use (if you do use one)? #ubuntuforlife #makingalinuxOSmyself :D --[[User:JayRulesXKCD|JayRulesXKCD]] ([[User talk:JayRulesXKCD|talk]]) 16:36, 14 September 2016 (UTC)<br />
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:Arch Linux. Although I'm new to Linux, I already love it!--[[Special:Contributions/162.158.69.39|162.158.69.39]] 19:07, 5 December 2016 (UTC)<br />
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::You use colons to indent replies. [[Special:Contributions/162.158.78.160|162.158.78.160]] 05:08, 27 July 2020 (UTC)<br />
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::Arch Linux here as well. [[Special:Contributions/162.158.222.123|162.158.222.123]] 11:41, 20 January 2022 (UTC)<br />
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I’d like to point out the oft overlooked fact that the majority of malware targets Windows based PCs not exclusively because *NIX systems are so Uber secure, but rather simply because historically Windows is the dominant OS for consumer grade computers. Malware and Adware have a financial motive and so it makes the most sense to write for an OS that holds more than 85% market share. This isn’t an excuse for Windows systems historically being underwhelming secure to put it mildly, but it is something of note.<br />
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Whooooo! good job, Randall![[Special:Contributions/108.162.246.108|108.162.246.108]] 21:12, 18 October 2016 (UTC)<br />
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Haha i use linux... on a VM---- {{unsigned ip|108.162.237.64}}<br />
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:I have a Raspberry Pi that filled up its SD card, as well as WSL. [[Special:Contributions/162.158.78.160|162.158.78.160]] 05:08, 27 July 2020 (UTC)</div>162.158.222.123https://www.explainxkcd.com/wiki/index.php?title=Talk:2555:_Notifications&diff=222659Talk:2555: Notifications2021-12-16T09:40:13Z<p>162.158.222.123: </p>
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I wrote that the time in the title text does not seem to have any special meaning, the only thing a quick google search gave me was the bible verse "Think not that I am come to send peace on earth: I came not to send peace, but a sword." which is irrelevant to the comic as far as I can tell. Is there something I missed? -- [[User:256 256.256.256|256.256.256.256]] ([[User talk:256 256.256.256|talk]]) 08:52, 16 December 2021 (UTC)<br />
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:I assume it has something to do with time zones, but not sure.[[Special:Contributions/162.158.222.123|162.158.222.123]] 09:40, 16 December 2021 (UTC)</div>162.158.222.123https://www.explainxkcd.com/wiki/index.php?title=Talk:2552:_The_Last_Molecule&diff=222575Talk:2552: The Last Molecule2021-12-14T16:44:08Z<p>162.158.222.123: </p>
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Unsuccessfully tried to search for a match to the image of the chemical compound. Did find this, which is difficult to use on a cellphone: OSRA: Optical Structure Recognition: https://cactus.nci.nih.gov/cgi-bin/osra/index.cgi [[Special:Contributions/172.70.211.172|1 not72.70.211.172]] 07:43, 9 December 2021 (UTC)<br />
:I've tried to search for SMILES of the molecule, but also got nothing: https://pubchem.ncbi.nlm.nih.gov/#query=C1(C2CC(CCC)C(CC)C2(CCCC))C%3DCC(C(%3DCCC(%3DC)CC)C(C)C)%3DC1 [[Special:Contributions/162.158.222.137|162.158.222.137]]<br />
::Let's name it Excacidin ;) [[User:256 256.256.256|256.256.256.256]] ([[User talk:256 256.256.256|talk]]) 07:19, 10 December 2021 (UTC)<br />
:: Here is updated SMILES taking into account comments below: N1(C2OC(CO)C(O)C2(OCCC))C=NC(C(=NCC(=O)O)N)=N1 [[Special:Contributions/162.158.222.123|162.158.222.123]] 16:44, 14 December 2021 (UTC)<br />
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I truly don't understand the God part of the current explanation. [[Special:Contributions/172.68.110.121|172.68.110.121]] 07:55, 9 December 2021 (UTC)<br />
:There is an article at [https://www.smithsonianmag.com/smart-news/humans-make-110000th-earths-biomass-180969141/ Smithonian Magazine] that sums it up quite nicely: Of the 550 gigatons of biomass carbon on Earth, animals make up about 2 gigatons, with insects comprising half of that and fish taking up another 0.7 gigatons. Everything else, including mammals, birds, nematodes and mollusks are roughly 0.3 gigatons, with humans weighing in at 0.06 gigatons.<br />
::About half of all known living species on earth are insects. Therefore if there was a god who created all life, it would be reasonable to assume he likes them. [[User:Bischoff|Bischoff]] ([[User talk:Bischoff|talk]]) 08:26, 9 December 2021 (UTC)<br />
::: 1 Ton = 10^3 kg = 1 Mg → 1 gigaton = 1 Pg (note, not pentagram!) --[[User:Slashme|Slashme]] ([[User talk:Slashme|talk]]) 02:27, 10 December 2021 (UTC)<br />
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Chemistry. I love chemistry :-) There is a concept called "Chemical Space" that I learned about in school. https://en.wikipedia.org/wiki/Chemical_space may help, in short: Chemical space is a huge but finite space of all possible atom arrangements in molecules. [[Special:Contributions/162.158.91.106|162.158.91.106]] 07:59, 9 December 2021 (UTC)<br />
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I've heard the claim, that we know less about our own ocean floor than we do about the surface of Mars several times before. Is there actually a credible source for this and how do we even quantify how much we know about either area? [[User:Bischoff|Bischoff]] ([[User talk:Bischoff|talk]]) 08:26, 9 December 2021 (UTC)<br />
:This essay might shed some light on the question. [[https://www.scientificamerican.com/article/just-how-little-do-we-know-about-the-ocean-floor/ Just How Little Do We Know about the Ocean Floor?]] From a geographical perspective, our maps of the ocean floor are much less detailed than those covering Mars. (5km resolution for ocean floor, 100m resolution for Mars - radar doesn't work underwater). [[Special:Contributions/162.158.107.18|162.158.107.18]] 09:25, 9 December 2021 (UTC)<br />
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The current explanation says that there are an infinite number of chemicals. Is that true? Source? Explanation how that is possible? <br />
Obviously the number of possible molecules is huge, but is it actually a literal, mathematical infinite? Given a finite observable universe, with presumably a finite number of atoms in it. There appear to be a finite number of elements which are stable for any appreciable amount of time and capable of forming molecules.<br />
It seems like there might be practical limitations to the size of a molecule, so that you can't keep making bigger and bigger ones just by adding more atoms/subunits? <br />
If you just keep adding carbon atoms to a diamond will you eventually reach a point where forces such as gravitation become a factor and the molecular bonds fail? I can imagine that long chain molecules light years long might reach point where other forces overwhelm the bond strength? [[Special:Contributions/108.162.246.76|108.162.246.76]] 09:10, 9 December 2021 (UTC)<br />
:For obvious reasons, as long as you limit the number of atoms involved the number of possible "molecules" is - in a mathematical sense - finite. (As there is only a finite number of reasonable stable elements.) But already simple things like polymers can bind millions of atoms in a single molecule. Together with the possible variations intrinsic to such polymers a simple "material" like phenolic resin [[https://en.wikipedia.org/wiki/Phenol_formaldehyde_resin]] is a mixture of more different chemical compounds (in a strict sense) than mankind can ever describe. For all practical application this compexity is not relevant, so no one really cares about.<br />
Additionally there is no clear boundary between typical molecules and other types of condensed matter, like crystals. Same applies to biochemistry. Does chemistry include bio-molecules? If yes, the chemistry guy have to include all the gene sequencing in their to-do list.<br />
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"how fast does light travel in one direction?" is not a good example for incompleteness in physics, because this question was settled by Michelson and Morley in the 19th century (answer: it travels with the speed of light)<br />
: It's not clear to me either what was meant here - seems out of place.<br />
:We know how fast light travels when it goes somewhere and comes back – that's ''c'' – but we don't know how fast it goes when only traveling in one direction. For example, light going at ''c''/2 in one direction and returning instantaneously in the other would still match our observations. We also can't reliably synchronize clocks over a distance because we'd either have to do it with a speed-of-light delay, or separate two clocks and find that relativity changed the timings. Of course, Occam's razor indicates that a consistent speed is more likely, but that's not proof. [[Special:Contributions/172.70.126.87|172.70.126.87]] 12:42, 9 December 2021 (UTC)<br />
:Observing two points (nominal source and nominal destination) from a third point perpendicularly off the mid-point between thoss two points, at an arbitrary distance, you ought to see if there's slowness or instaneity involved (at least make a comparison between bidirectional traversal). This does not remove a response bias in the signal from either end as sent towards the recorder at the observation point, but as the stand-off is increased it makes both observation paths nearer and nearer to parallel and so significantly removes the quantifiable initial 'sideways bias' that may exist.<br />
:I leave it as an excercise to the reader to produce the reasons why this might not practically work to quash all such 'inbuilt universal asymmetry', but it's a good start! [[Special:Contributions/172.70.90.141|172.70.90.141]] 13:21, 9 December 2021 (UTC)<br />
:I genuinely don't understand the confusion being proposed here; in practice it's trivial to synchronize a single photon emitter with a single photon detector (such as a PMT) and confirm the speed of light across a single path, with no return trip involved. As far as I know there is know precidence in QM to suspect bidirectional travel could be a special case.<br />
:I like Veritasium as much as the next guy, but I don't think that this one is a serious debate like the other examples. If you're going to consider something like this a great unsolved mystery in physics, I'm sure there are countless other questions just like this for almost every topic in physics and not everything can be a great unsolved mystery.[[Special:Contributions/172.70.134.23|172.70.134.23]] 17:37, 9 December 2021 (UTC)<br />
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To quote Randall Munroe in https://what-if.xkcd.com/114/, "The whole universe is matter, as far as we can tell. No one is sure why there is more matter than antimatter, since the laws of physics are pretty symmetrical, and there's no reason to expect there to be more of one than the other. Although when it comes down to it, there's no reason to expect anything at all." Antimatter aside, this shows that the laws of the universe are sometimes asymmetrical. I also like the point that "when it comes down to it, there's no reason to expect anything." Why should we expect the speed of light to be symmetrical? There's no real reason to. [[User:Beret|Beret]] ([[User talk:Beret|talk]]) 14:53, 9 December 2021 (UTC)<br />
:On the contrary, without any such thing as the æther (the fundament through which we would be passing) there is no reason to expect the speed of light (in any given frame of reference) to be asymmetrical. Relativistic frame-dragging and other distortions due to (or resulting in!) accelerative forces will act accordingly, but not change ''c'' itself, in proper calculations, as a function to direction. [[Special:Contributions/172.70.86.12|172.70.86.12]] 16:02, 9 December 2021 (UTC)<br />
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::https://en.wikipedia.org/wiki/One-way_speed_of_light In any case, the point is that there is no reason to expect light speed to be symmetrical, either. Asymmetry in this case is not due to frame dragging, it would be some fundamental feature of photons or the universe. There is currently no experimental way to test this. [[User:Beret|Beret]] ([[User talk:Beret|talk]]) 17:00, 9 December 2021 (UTC)<br />
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Maybe we can cite one of some famous declarations of physicist saying the physics is almost done [https://nautil.us/blog/the-comforting-certainty-of-unanswered-questions (taken from this site)] :<br />
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:The British scientist William Cecil Dampier recalled his apprenticeship at Cambridge in the 1890s: “It seemed as though the main framework had been put together once for all, and that little remained to be done but to measure physical constants to the increased accuracy represented by another decimal place.” British physicist J. J. Thomson: “All that was left was to alter a decimal or two in some physical constant.” American physicist Albert A. Michelson: “Our future discoveries must be looked for in the sixth place of decimals.”<br />
:My physics professor from freshman year: "If you're ever in a room with physicists who say that the physics of Earth are done, and there's nothing else left to calculate, ask them "what about turbulence?". You'll be sure to get some dirty looks."[[Special:Contributions/108.162.246.122|108.162.246.122]] 21:08, 9 December 2021 (UTC)<br />
--[[User:Marceluda|Marceluda]] ([[User talk:Marceluda|talk]]) 15:32, 9 December 2021 (UTC)<br />
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I'd argue that fusion on earth is an engineering problem, not a matter of physics completeness (yeah, engineering is just applied physics and math just theoretical physics and biology what happens when you close two physicists in a room for too long, but still). Also, the problem of the symmetry of light speed is, from the present understanding of physics, a matter of metaphysics. [[Special:Contributions/172.68.94.143|172.68.94.143]] 13:42, 10 December 2021 (UTC)<br />
:Having worked in fusion research, I'd say it's still a physics problem because we don't yet know if it's physically possible for a burning plasma to be confined for long enough on a small enough scale to create a viable power plant. It's not necessarily just a question of designing the right machine, if you see what I mean. And if it was, I'd like to think we'd find a few hundred billion of dollars of funding and just get it done. IMO the reason it's not a funding priority is that we can't be sure it would work with _any_ amount of money. That said, while it's potentially a question of great value to humanity, I don't think it's significant in terms of the completeness of physics as a field. --[[User:192·168·0·1|192·168·0·1]] ([[User talk:192·168·0·1|talk]]) 15:18, 10 December 2021 (UTC)<br />
:To rant further about fusion funding, we don't know whether we can win any given war either but that doesn't stop us spending trillions of dollars on them. Maybe if we called fusion research "the war on paying for electricity / wrecking the environment" maybe we'd get it sorted. --[[User:192·168·0·1|192·168·0·1]] ([[User talk:192·168·0·1|talk]]) 15:23, 10 December 2021 (UTC)<br />
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Regarding the final molecule, using the above mentioned cactus website optical recognition I got: *[C@H](*CC[C@H](C)[C@H](C1CC1C[C@H](CC)CCC)C2[C@H](*)[C@@H]2C)CC3C*(CCC)C(CCC)[C@H]3CCCCC, which isn't recognized as a molecule. Anyone have any better ideas on if there is a similar known molecule? [[User:Stickfigurefan|Stickfigurefan]] ([[User talk:Stickfigurefan|talk]]) 17:16, 10 December 2021 (UTC)<br />
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Regarding the completeness of chemistry, I see no reason why a DNA molecule can't be longer than observable universe (it definitely wouldn't collapse into black hole ; obviously, tugging on it would break it somewhere). Regarding the completeness of biology, what organism would such molecule encode? While, mathematically speaking, observable universe is finite, I would consider this idea alone to ensure chemistry and biology can't ever be complete. -- [[User:Hkmaly|Hkmaly]] ([[User talk:Hkmaly|talk]]) 23:35, 10 December 2021 (UTC)<br />
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Should we really use "citation needed" for a quotation, where we might actually want a citation? We're only supposed to use that ironically here. [[User:Barmar|Barmar]] ([[User talk:Barmar|talk]]) 17:46, 10 December 2021 (UTC)<br />
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== Why citation needed? ==<br />
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I saw a citation needed about the Higgs Boson. Is it needed for humor? The higgs boson isn't obvious.--[[Special:Contributions/172.70.34.191|172.70.34.191]] 19:14, 10 December 2021 (UTC)<br />
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== Circular reasoning ==<br />
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I think something could be added about how determining how "complete" is a discipline already requires a complete knowledge of that discipline, even if we limit this to the inappropriate "number of known entities" approach. Some plausible estimates are naturally possible and a historic example seems to be more in line with the current explanation. A good fit seems to be how in physics the proton, neutron and electron model seemed at some point quite complete and was less crowded than the current one, still not sure how much of this understanding is a myth or how to put it in the explanation, so I prefer to leave it to someone else. For biology Wikipedia has {{w|Biological dark matter}} and the more theoretical {{w|Shadow biosphere}}, in case the number of unstudied multicellular organisms isn't sobering enough. [[Special:Contributions/172.70.98.153|172.70.98.153]] 02:07, 12 December 2021 (UTC)<br />
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== Serious hypothesis for the molecule's structure ==<br />
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I'm not sure why everyone keeps interpreting the picture as only containing carbon atoms. The leftmost moiety is clearly an ''O''<sup>2</sup>-substituted furanosyl group; exactly which furanose it is is uncertain, since the stereochemistry is not indicated at all. It could be <small>D</small>-ribofuranose, <small>D</small>-arabinofuranose, <small>D</small>-xylofuranose, <small>D</small>-lyxofuranose, or any of their <small>L</small>-enantiomers.<br />
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The central ring best matches the pattern of a 1,2,4-triazole, just looking at the bond patterns. It is consistent with how I've seen them in other compounds. Similarly, the rightmost group is clearly the -COOH of a carboxylic acid.<br />
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Probably the most ambiguous group is the one second from the right. Based on the bond patterns alone, it would be consistent with an amidine, which is probably the possibility most likely to occur in real compounds. However, ''N''′-monosubstituted amidines seem pretty rare based on a cursory search, and most likely tautomerize quickly into ''N''-monosubstituted amidines. I don't have any other idea of what it could be, though.<br />
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I strongly suspect that the furanose is <small>D</small>-ribofuranose. The leftmost three groups can be seen as a modification of [[wikipedia:Adenosine|adenosine]], which is one of the nucleosides found in DNA. In addition, '''the majority of this molecule exactly matches the antiviral drug [[wikipedia:Taribavirin|taribavirin]]''', which is used against hepatitis C and influenza. In fact, the drug may very well have been the inspiration for this molecule. The only two differences are an ''O''<sup>2</sup>-propyl substitution on the ribofuranose, and an ''N''′-(carboxymethyl) substitution on the amidine.<br />
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Assuming this interpretation of the molecule's structure is correct, its preferred IUPAC name (PIN) is "[(amino{1-[(2''R'',3''S'',4''R'',6''R'')-4-hydroxy-5-(hydroxymethyl)-3-propoxyoxolan-2-yl]-1''H''-1,2,4-triazol-3-yl}methylidene)amino]acetic acid". [[User:LegionMammal978|LegionMammal978]] ([[User talk:LegionMammal978|talk]]) 05:29, 12 December 2021 (UTC)</div>162.158.222.123https://www.explainxkcd.com/wiki/index.php?title=2509:_Useful_Geometry_Formulas&diff=2174112509: Useful Geometry Formulas2021-08-31T19:27:10Z<p>162.158.222.123: fixed formula for triangle+semiellipse A = πb^2 + πbh</p>
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<div>{{comic<br />
| number = 2509<br />
| date = August 30, 2021<br />
| title = Useful Geometry Formulas<br />
| image = useful_geometry_formulas.png<br />
| titletext = Geometry textbooks always try to trick you by adding decorative stripes and dotted lines.<br />
}}<br />
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==Explanation==<br />
{{incomplete|Created by a STRIPED AND DOTTED TEXTBOOK ILLUSTRATOR. Explain the formulas for each of the areas, and also the correct formula for the 3D object they seems to represent. Do NOT delete this tag too soon.}}<br />
This comic showcases area formulae for four two-dimensional geometric shapes which each have extra dotted and/or solid lines making them look like illustrations for 3-dimensional objects - the first, a simple equation for a circle, the second an equation for a triangle with an elliptical base, the third an equation for a rectangle with an elliptical base and top, and the fourth a hexagon consisting of two opposing right angled corners and two parallel diagonal lines connecting their sides. In each case, only the outlines of each shape have any practical meaning.<br />
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Such illustrations are commonly found in geometry textbooks, which need to depict three-dimensional figures on a two-dimensional page. They use slanted lines to indicate edges receding into the distance, and dashed lines to indicate an edge occluded by nearer parts of the solid. The joke is that the formulae given here are for the area of each two-dimensional shape as drawn, not for the surface area or volume of the illustrated 3D object (as would be shown in the geometry textbook). The title text continues the joke by claiming that the dotted lines are simply decorative.<br />
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The illustrations depict the following plane or solid figures, depending on the interpretation.<br />
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<b>Top left.</b>&emsp;A circle (illustrating a sphere) with radius r. The equation for the area of a circle is A = πr<sup>2</sup> as is given below the figure. The surface area of a sphere is 4πr<sup>2</sup> , which is what we would have expected from the figure. The volume of a sphere is <sup>4</sup>/<sub>3</sub>&nbsp;πr<sup>3</sup>.<br />
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<b>Top right.</b>&emsp;An isosceles triangle of height h combined with a semi-ellipse with semiaxes a and b (illustrating a right elliptic cone). The area of the triangle is bh, and the area of the semi-ellipse is <sup>π</sup>/<sub>2</sub>&nbsp;ab. The equation for this area is A = 1/2 πab + bh as is given below the figure. However, if this was in a text book then a=b even if drawn like this, thus the cone has a circular base, in the 3D drawing. Such a "normal" cone has an area A = πb^2 + πbh. (a=b). That cones volume would be πr^2*h/3. Taking the 3D drawing literal with a≠b then the lateral surface area of a right elliptic cone is<br>2a√(b<sup>2</sup>&nbsp;+&nbsp;h<sup>2</sup>)&nbsp;∫<sub>0</sub><sup>1</sup>&nbsp;√(<sup>a²h²(t²-1)&nbsp;-&nbsp;b²(a²+h²t²)</sup>/<sub>a²(t²-1)(b²+h²)</sub>)&nbsp;dt. The volume is <sup>π</sup>/<sub>3</sub>&nbsp;abh.<br />
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<b>Bottom left.</b>&emsp;A rectangle of width d and height h between two semi-ellipses of semi-minor axis r (illustrating a right elliptic cylinder). The area of the rectangle is dh and the area of the two half-ellipses equals the area of one full ellipse, <sup>π</sup>/<sub>2</sub>&nbsp;dr. The equation for this area is A = d(πr/2 + h) as is given below the figure. For a 3D representation the cylinder has circular base so d = 2r, (not elliptical as indicated in the 2D drawing). Such a cylinder has a surface area of 2πr^2 + πdh. The volume of such a cylinder is πr^2h. Taking the 3D drawing literal with d≠2r then the lateral surface area of the right elliptic cylinder is 4h&nbsp;∫<sub>0</sub><sup>1</sup>&nbsp;√(<sup>1&nbsp;-&nbsp;t²(1-4r²/d²)</sup>/<sub>1&nbsp;-&nbsp;t²</sub>)&nbsp;dt. The volume is <sup>π</sup>/<sub>2</sub>&nbsp;rdh. <br />
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<b>Bottom right.</b>&emsp;A convex hexagon with three pairs of parallel sides and two right angles at opposite vertices (illustrating a rhomboid-based prism). The area of the rectangle representing the front face of the prism is bh. The area of the upper parallelogram is db&nbsp;sin&nbsp;θ. The area of the right parallelogram is dh&nbsp;cos&nbsp;θ. The equation for this area is A = bh + d(b sinθ + h cosθ) as is given below the figure. The surface area of the prism would be 2bh&nbsp;+&nbsp;2db sinθ&nbsp;+&nbsp;2dh. The volume is bdh sinθ.<br />
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In the history of the development of computer-generated 3D graphics, calculations of the apparent visual area taken up by the projection of a volume may have been useful in occlusion-like optimizations, where each drawn pixel may be passed through many fragment shaders.<br />
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==Transcript==<br />
{{incomplete transcript|Do NOT delete this tag too soon.}}<br />
:[Four figures in two rows of two, each depicts a two-dimensional representation of a three-dimensional object, with solid lines in front and dotted lines behind. Each figure has some labeled dimensions represented with arrows and a formula underneath indicating its area. Above the four figures is a header:]<br />
:Useful geometry formulas<br />
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:[Top left; a 'sphere', or a circle with a concentrict half-dotted ellipse sharing its major axis, with the shared semi-major radius labeled 'r']<br />
:A = πr²<br />
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:[Top right; a 'cone', or a triangle with the base replaced by a half-dotted ellipse. The triangular/conic height is 'h'. The ellipse in place of the base has semi-minor axis 'a' and major axis 'b']<br />
:A = 1/2 πab + bh<br />
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:[Bottom left; a 'cylinder', or a pair of ellipses connected by verticals. The vertical side/edge is shon as height 'h'. The ellipses have semi-minor axis r, in the lower half-dotted ellipse, and major axis d, across the upper ellipse]<br />
:A = d(πr/2 + h)<br />
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:[Bottom right; a 'rhomboid-based prism', or a semi-regular hexagon with identical pairs of vertical, horizontal and diagonal sides, plus three more congruent pairs (one of each dotted) all linking inwards from their own vertex to meet at one of two complimentary points within. The representative horizontal line is marked 'b', a vertical is 'h', a diagonal as 'd'. Between the base horizontal and the lower internal diagonal is a non-'rightangled' angle 'θ']<br />
:A = bh + d(b sinθ + h cosθ)<br />
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[[Category:Math]]</div>162.158.222.123