I think there's a problem with this.
M. B. - "The length of the dog's chain is pi."
The dog should be able to wrap the leash entirely around the lighthouse, each way, coming back to where it's attached.
The drawings show it only going halfway. I'd swear the drawing is pi/2.
Unless I'm missing something.
If true, the math would be similar, but he's got a lot more room.
Arf