1. Ra4 Qxa4
2. Rh3 Kd4 or Ke4 or Kf4
3. Rh4 any black move
4. Rxa4 black queen is gone.
Or
1. Qc8
2. Rh3 Qxh3
3. Ra3 any king move
4. Rxh3
Or
Qf8? Then Queen is gone w/o any compensation by Rh3 followed by Ra3 then Rxf6
Or
Any other queen move, Rh3 mate.
Ra4
to understand this Rook sac(-rifice),
remember:
- the move cuts off a vector(s)for check for the Black queen,
- mate in☝️one move if ignored
- the king canNOT approach the other king
Qxa4, Rh3 , Black king moves to the 4th rank, Rh4 , Black king moves, Rxa4
🤷🏻♀️#TheEndIsNear