This reminds me of this problem:
Hang a picture using two nails, s.t. if either nail is removed, the picture falls.
ETA: this is a math problem, not a lateral thinking problem. I was too lazy to write out all the caveats, e.g. “the nails go in the wall”. Non lateral answer:
ETA: here’s a video solving the 4-nail version. Skip to 1:10.
