"A painter is an artist."
Translation:Ressam bir sanatçıdır.
"A painter is an artist" is a general, 'authoritative' type statement, and this type of statement gets the -dir suffix to the attribute. You could say "Ressam bir sanatçı" when you look at a painting and want to express your opinion that "The painter (who did this painting) is (really) an artist!"
As far as I understand, "Ressam bir sanatçıdır" and "Ressam sanatçıdır" would both work for "A painter is an artist." Your answer may have been rejected because you omitted the -dir suffix at the end.
what does the "dir"mean at the end? the sentence can be with or without it apparently.
I wrote: ressam sanatçı, it is correct, but seems like Tarsan speaking to me :-D