John Casey
Irish geometer (1820-1891) · Ireland · On the map · Academics · Died at 70
John Casey was a respected Irish geometer. He is most famous for Casey's theorem on a circle that is tangent to four other circles, an extension of Ptolemy's theorem. However, he contributed several novel proofs and perspectives on Euclidean geometry.
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A typical day, 30 days to 24 August 2026
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About this person
He and Émile Lemoine are considered to be the co-founders of the modern geometry of the circle and the triangle.
Country
Ireland
Category
Academics
Type
Academic
Status
Deceased
Dates
Lived 1820 to 1891 · aged 70
