A lack of personal insight regarding a problem from the 2019 College of Charleston Math Meet Level III Written Test (#25: about the area illuminated by a spotlight) led to an encounter with the spheres of the 19th century French mathematician Germinal Dandelin. In this talk, we learn about Dandelin spheres and how they could be used to solve the CofC problem (and maybe also see a sketch of a sphere-less solution).

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