@Limitless When you vote to close a question as exact duplicate you're asked for a link to the question you claim it is a duplicate of. As soon as five users have voted to close, even though their reasons for doing so are wildly divergent, the system closes the question.

@HenningMakholm I see. Why did you vote to the close the question, if I may know?

Eh this might seem like a strange thing to ask. But a friend asked my why it is impossible to construct an angle of 70 degrees. I said that if this was possible, then it would imply that the construction of a Convex Polygon with sides n=36/11 is possible to construct. But by Gauss`lemma, this is not. Is this good enough of an argument?

@Limitless I thought that the ground has already been covered in the first of the now-linked question. (As a matter of fact it was me who mistakenly thought that the geometric-series one would be an even better original to link to, but I deleted that comment after about half a minute, and stand by closing it as a duplicate of 18983 instead. I'm somewhat surprised that the system chose to write in the link to the false original; I thought that only the "most popular" original would be linked).

@N3buchadnezzar If you could construct a 70° angle, you could subtract an (easily constructible) 60° angle to make 10°. But 10° is well known to be impossible.

@HenningMakholm Is $10^{\circ}$ well known to be impossible to construct?

@HenningMakholm, in my humble opinion, the way that the ground is covered is not sufficient for the audience. The author of the question stated he did not understand the more complex explanations. I assume that the language of the question linked to, while highly informative, is completely inaccessible to him.

@N3buchadnezzar Yes; it's part of the standard argument against general angle trisection.

@Limitless I think most of the close votes must have been cast before the OP edited in that statement. Mine certainly was.

@HenningMakholm, is there any way to reverse this?

I think the edit heavily changed the situation.

Man this makes me want to study Galois Theory

Due to my low rep, I can't cast a re-open vote.

Does anybody know anything about the French language and its usage?

In math.

@N3buchadnezzar I should be studying for an exam on Galois theory right now!

@AntonioVargas Do you enjoy Galois Theory ?

@Limitless I've voted to reopen, but there's no easy way to rally for such votes, save for starting a meta thread. And such one-issue meta threads are slightly frowned upon.

@HenningMakholm, yes, I can see why it would be frowned upon. However, I am a little displeased with the effort I put in and the fact it's a good question. Can the OP at least accept answers?

@Limitless Yes, the only hard effect of closing is that new answers cannot be posted.

@N3buchadnezzar It's okay. I'm a little jaded because my teacher and I don't jive. But I like the concept and theory behind field extensions a lot, which Galois theory relies on.

@HenningMakholm, I see. Thank you for the information. I wasn't fully aware what closing did.

@AntonioVargas Well from what I have heard it gives some nifty tools to prove various things, like irrationality of numbers, quartic formula, trisection and so on. I might take it, but then I need to focus myself in Algebra. I do not know if that is the path I want to take yet.

(Also, high-rep users can vote to delete questions after they are closed. But that hardly ever happens with questions that are not pure nonsense or spam).

@N3buchadnezzar But Galois theory is algebra.

Ofcourse I know that Galois Theory is algebra, but in order for me to take it I need to take a few courses beforehand. and I do not know If I want to take the path of an "algebraist"

Ah. But even so, I think the basics of Galois theory belong in the groundwork undergraduate "breath" set, even without any particular algebra focus. (I took it once, didn't like it much and cannot reproduce the arguments -- but am glad to have some idea of how it works nevertheless).

But I guess I need to have some knowledge of rings, fields and such before taking it

Yes. (Which is also part of the basic mathematician's toolkit, of course). At least groups and commutative rings. What there is to say about fields is Galois theory itself ...

@HenningMakholm I know there is quite some time since you graduated, but what courses did you fancy the most ?

@robjohn I've got Stein's book :-)).

@N3buchadnezzar Hmm. Good question. The way I remember it is actually that by the time I'd gotten to the third (final) year of mathematics, I had soundly made up my mind to switch to computer science and just took mathematics courses in order to get them done with. The ones I didn't drop out of halfway through tended to be algebra rather than analysis, though.

Has anyone read the art of programming?

@Rob no

@N3buchadnezzar Check it out

@N3buchadnezzar The art of computer programming

@JonasTeuwen which book?

@robjohn Princeton Lectures in Analysis IV.

@JonasTeuwen Ah, that's the one you didn't have?

@robjohn Yes. Very cute it is I can tell you. I approve of the topics.

@JonasTeuwen I will have to get the set.

@robjohn I can surely recommend it :-).

@robjohn You could start with the last one, that one is the most interesting (as they are quite expensive to buy in one go, but I'm of course not aware of how wealthy you are, but if you want to start with one, the last one is good :-) and then you can go down from there :-))

I will either get them through Amazon or see what they have at UCLA next time I am on campus

At the library? They sure should.

@JonasTeuwen The library? I haven't been there in years. I usually find things online. I'll have to try it.

@robjohn Yes.

@robjohn But a hardcopy is nice 8-).

Good night, ding ding ding!

is there a simple argument for why given $M$ an $m\times n$ matrix with entries in a PID there are matrices $A$ and $B$ such that $AMB$ is diagonal? when given a specific case one can do it algorithmically

but as always i would love to just know an existential argument

@MarianoSuárezAlvarez, do you have any insight?