Figure[White to move]

Again the idea in simplest form. White has a rook and a bishop against Black’s queen. How to play from here? Start by examining your check. White’s only one is Ra1+. Black has to move his king to b8. White sees that this would put the king right behind the queen on the same dark-squared diagonal; this invites 2. Bf4, pinning the queen with protection from the pawn on g3. White wins.