Is it possible to win (black or white) in this position?
[fen "2k5/5R2/8/4K3/r7/8/8/8 w - - 0 1"]
Is it possible to win (black or white) in this position?
Of course it is. Both black and white have mating material. They each have a rook but a victory for either of them would require the opponent to blunder. For instance if white were to play Rc7 blundering the rook then black can force checkmate and if black were to play Re4 white could take and again force checkmate.
Either player could also inexplicably resign which would also end the game in favour of the opponent.
However with reasonable play by both sides it is a draw.
At best play it is a draw, though it is possible for either white or black to win because both of them have a rook. Though, for either side to win, the other side would have to blunder or, obviously, resign.