For my inner eye, I can see that the circle will rotate half a circumsphere to get around the corner. But I can’t really explain why. It’s the same distance.

For my inner eye, I can see that the circle will rotate half a circumsphere to get around the corner. But I can’t really explain why. It’s the same distance. I get that when a road turns left, it’s longer on the right side, but these are lines that have no width and so there’s no stretch and by definition we’ve kept the length the same.