Mate in 5 Exercise 16

White plays and wins in 3 moves https://lichess.org/STif6wBx

1. Kc2 Ka2 2. Ra5 Ka1 3. Rxa3#

The analysis board does checkmate in 5 moves

1. Kc3 Ka2 2. Ra5 Ka1 3. Rxa3+ Kb1 4. Ra5 Kc1 5. Ra1#

Source:

https://www.amazon.com/Chess-Puzzles-Advanced-Expert-Level/dp/B0917YQZP1