This is the 15471st most frequent Russian word.
председателю
"To the chairman."
The word 'председателю' is in the dative case, indicating the indirect object of the sentence, i.e., the recipient of the letter.
Я написал письмо председателю.
I wrote a letter to the chairman.
The usage of 'председателю' in this sentence is in the dative case, representing the person to whom the explanation is directed.
Объясните проблему председателю на собрании.
Explain the issue to the chairman at the meeting.
In this sentence, 'председателю' is also used in the dative case, showing the recipient of the documents being handed over.