• Why bicontinuity is the right condition for topological equivalence (homeomorphism): if continuity of the inverse isn’t required, then a circle could be equivalent to a line (.99999 and 0 would be neighbours) — Minute 8 or so.
  • Geometric construction (no complex numbers) of the circle group.
  • Pappos’ theorem. (Minute 31)
  • Pascal’s theorem.
  • Desargues’ theorem.
Hat tip to +Ozymandias Haynes.

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