Euclid:Proposition/XIV/3

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Proposition

In the words of Hypsicles of Alexandria:

If there be an equilateral and equiangular pentagon and a circle circumscribed about it, and if a perpendicular be drawn from the centre to one side, then
$30$ times the rectangle contained by the side and the perpendicular is equal to the surface of the dodecahedron.

(The Elements: Book $\text{XIV}$: Proposition $3$)


Sources