📜 Theorem, law or theory

Ceva's theorem

Teorema de Ceva

Date
1678 · confidence high
Place
Milan, Lombardy, Italy
Credited to
Giovanni Ceva; proved centuries earlier by Yusuf al-Mu'taman ibn Hud
Field
Knowledge & symbols

⚠️ Disputed: the sources disagree.

What was discovered

Ceva published in 'De lineis rectis' (1678) the theorem giving the condition for three cevians of a triangle, drawn from each vertex, to meet at a single point, via a product of segment ratios. The result had already been proved in the 11th century by the mathematician-king Yusuf al-Mu'taman ibn Hud of Zaragoza, whose work fell into obscurity and was not rediscovered until 1985.

The exact city where Ceva worked out the result is not confirmed; he was a professor in Mantua/Milan around that time. The Andalusian mathematician Yusuf al-Mu'taman ibn Hud had already proved it in the 11th century, but his work was not rediscovered until 1985.

What it led to

  • Generalizations to higher-dimensional simplexes
  • Extensions to spherical and hyperbolic geometry
  • Link to Menelaus's theorem

Built on

  • Classical Euclidean affine geometry

Links

Sources✓ verified 2026-09-28