Re: [math-fun] Just a rock and a string

Maybe someone already answered this, but if not, this is a famous problem in geometry. See Croft's paper "A net to hold a sphere", available on the web. I saw this mentioned in the collection of problems in geometry edited by (I think) Goodman, Pollack, et al. It might also be mentioned in Croft and Guy's Unsolved Problems in Geometry. Neil