All you need to know about Carpenter's Square - 29

Diagram 29.1: White to play

We've seen very similar patterns while studying Shape 23 and 24. Just to repeat here to make the series complete.

Diagram 29.2: Solution

White 1 is clearly the only move. Black 2 is the best answer. White 5 is also the only correct move. The result is a ko.

Diagram 29.3: Black fails

Black 2 is a poor answer. It's never a good idea to reduce your own eyespace. The corner is dead.

Diagram 29.4: Black fails

Black 6 is useless.

Diagram 29.5: White fails

White 5 here is incorrect. Black 6 is good. The corner would end up in seki.

Conclusion: Diagram 29.2 is the best sequence for both sides.