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Theorem

Pitot Theorem

Geometry

The Pitot Theorem states that a convex quadrilateral has an inscribed circle tangent to all four sides if and only if the sums of the lengths of its two pairs of opposite sides are equal. Named for Henri Pitot, it is a classical characterization of tangential quadrilaterals, the quadrilateral counterpart to the simpler fact that every triangle always has an inscribed circle.

Facts
Statement
In a tangential quadrilateral the two pairs of opposite sides have the same total length. 1
Proof Year
1725 1
Classification
Statement Form
Identity or Equation 1
Connections

Has Statement Form

Equation, Concepts

Entity-backed identity for the statement-form enum value this theorem already carries, resolved to a mathematics concept by an explicit value-to-entity map (phase 3 bucket conversion, docs\design_entity_backed_browse_buckets_20260928.md). The statement-form fact itself stays on the theorem unchanged.

Identity, Concepts

Entity-backed identity for the statement-form enum value this theorem already carries, resolved to a mathematics concept by an explicit value-to-entity map (phase 3 bucket conversion, docs\design_entity_backed_browse_buckets_20260928.md). The statement-form fact itself stays on the theorem unchanged.

In Branch

Source Pitot theorem (Wikipedia)
Sources
1. Pitot theorem (Wikipedia)
  • Statement and converse, first sentence
    in a tangential quadrilateral the two pairs of opposite sides have the same total length.
  • History: Henri Pitot proved his theorem in 1725
  • In Branch: Geometry, Lead sentence
    The Pitot theorem in geometry states that in a tangential quadrilateral the two pairs of opposite sides have the same total length
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