Russian Language Stack Exchange is a question and answer site for students, teachers, and linguists wanting to discuss the finer points of the Russian language. It only takes a minute to sign up.
Sign up to join this community
I read the following sentences:
Две девочки разговаривают друг с другом.
Мужчины помогают друг другу.
Они танцуют друг с другом.
I think the meaning in each sentence is something like the followings:
The two girls talk with each other.
Men is helping each other.
They are dancing together.
But I don't get when to use друг с другом and друг другу. What is the difference between them?
That's simply Dative vs. Instrumental case issue. There is natural (although hidden in your translation) correspondence here:
dance with --> Instrumental case --> танцевать друг с другом
help to --> Dative case --> помогать друг другу
The verb разговаривать yet differs: in Russian разговаривать denotes "cross-personal" communication exclusively, so it requires Instrumental "with". If you need Dative "to", you have to use imperfective form "говорить" (note that both are OK, though slightly different: говорить друг другу and говорить друг с другом).
It actually depends on verb syntax. Compare:
разговаривать (с кем?) - с другом
помогать (кому?) - другу
танцевать (с кем?) - с другом
