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Gretchen Wieners once advocated that everyone start saying “fetch,” but don’t stop there. Don’t be a tosser. Use them all.

In projective geometry, Desargues's theorem, named after Girard Desargues, states: Two triangles are in perspective axially if and only if they are in perspective centrally. Denote the three vertices of one triangle by a, b and c, and those of the other by A, B and C. Axial perspectivity means that lines ab and AB meet in a point, lines ac and AC meet in a second point, and lines bc and BC meet in a third point, and that these three points all lie on a common line called the axis of perspectivity. Central p...

A book from the stand-up mathematician that makes math fun again!Math is boring, says the mathematician and comedian Matt Parker. Part of the problem...