Questions & Answers about Maðurinn er ríkur.
Because -inn is the definite article attached to the noun.
- maður = man
- maðurinn = the man
Unlike English, Icelandic usually puts the at the end of the noun instead of using a separate word.
So in this sentence:
- Maðurinn = the man
-inn is the masculine singular form of the attached definite article in the nominative.
In other words, it is the Icelandic way of saying the here.
With this noun:
- maður = man
- maðurinn = the man
You do not say a separate word for the in this sentence.