"Dzień dobry, jestem lekarzem."
Translation:Good morning, I am a doctor.
When the previous comment was written, I asked several natives about the acceptability of "good day". They all wrote that it sounds totally out of date and would just seem weird if you said that.
And for afternoon, you just use "Good afternoon" ;) Which is accepted, of course.
Well, Google Translate is not really the best source of knowledge.
It's a tough decision to make. I understand that "hello" is not that informal as it has always seemed to me. But still we believe it's safer to go with the more formal answers. You will rather not say "dzień dobry" to your friend, at least seriously.