Neuberg cubic
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Described at
Under the rotations with center O (resp. H) and angles +/-2π/3, the Neuberg cubic is transformed into two other circular cubics K001+ and K001–. These two cubics generate a pencil of circular cubics passing through O (resp. H) and therefore having six other common points. This pencil contains the Neuberg cubic itself hence there are two equilateral triangles with center O (resp. H) inscribed in the Neuberg cubic. See the two figures below.
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