"Это известная проблема."

Translation: It is a well-known problem.

[Chickensnake]

Why not эта if проблема is feminine?

[2E3S]

эта известная проблема="this well-known problem", это="it is" (это - человек) or neuter "this" (это имя) or indefinite "it" (я вижу это)

[Chickensnake]

Thank you.

[sp.ark]

This is a well-known issue.
Is this definitely not correct?

[deactivated user]

surely saying "it's a common problem" is more realistic than saying "it's a well-known/famous

[petrenko]

A problem can be very common, but almost unknown e.g. a fault in a model of washing machine that has not yet been recalled.

[PowlPre]

Nothing to do with realistic, that translation would just be wrong

[Yakuul]

How about "This is the well-known problem"? why not definite?

[eviniesta]

The meaning is "important problem"? I'm not a native speaker of English but "well-known problem" sounds quite weird to me.

[LutherF]

To say "well-known problem" does sound kind of strange, but it could be possible under certain circumstances. "Well-known issue" is a better collocation in English. I think the translation here is simply showing that the Russian word известный can be translated as well-known.

[flint72]

This is perfectly natural to me (Hiberno- and British-English speaker), but that may be because I am a mathematician! There are many famous problems, or well-known problems, in mathematics and theoretical physics, some of which have $1,000,000 prizes!

[elsantodel90]

Being a computer scientist, I agree:

https://en.wikipedia.org/wiki/NP-completeness

"The list below contains some well-known problems that are NP-complete when expressed as decision problems."

I take notice though of the native speakers comment that "Well-known issue" might be more natural when the problems are not mathematical in nature but a "real world issue".

[AlexFromAus]

Do you think "well-known problem" would be a phrasing used by better speakers?
Simple folk might say "everyone knows it" :p

[Madame-patate]

Does the word "извесная" have anything to see with the word "извините" ? 'cause they look very much alike ^^

[2E3S]

Известная and извините look alike only because they have the same prefix из- and the same first root letter в. Taking the root we have "вест" and "вин" which are clearly different. Весть=a piece of news, вина=guilt.

[Madame-patate]

Alright ! And what does из- indicate ?

[2E3S]

wiktionary. I'm not sure on which meaning this word is based, I guess, it's about completeness, it's buried in the language history.

It's like there is a word "go on" and you ask "what does on indicate?".

[Madame-patate]

I see, thanks for your time ^^

[Roman_Key]

"It's a notorious problem." was marked as wrong. Should it be accepted?

[alezrozent]

Notorious=пресловутый (печально известный) аnd not известный. I'm a native Russian.

[Solomon502280]

"This famous problem" wrong?

[2E3S]

Look at the top comments here and especially at this article https://forum.duolingo.com/comment/11536858

[ArthurKock1]

Points to one of the official Millennium problem statements.

http://www.claymath.org/millennium-problems

[MountZion]

is there a difference between common and well-known?

[eels71]

also known as global warming

[SpookyHams]

This is a common problem is a much used sentence in English

[Keloudi]

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