Mate with king and rook
The rook gives the check; your king stands facing the other, one square away.
Rook and king mate too, and the shape is similar. The marked squares are the black king's exits, and the one taking all three is your king on e6, standing right in front of the other, one square away. That face-to-face position has a name: the opposition. Without it the mate does not come.
Deliver mate in one move.
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