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Theorem

Exterior Angle Theorem

Geometry

The exterior angle theorem is Proposition 1.16 of Euclid's Elements. It states that the measure of an exterior angle of a triangle is greater than the measure of either of the triangle's remote interior angles, the two interior angles not adjacent to that exterior angle. This description is adapted from Wikipedia contributors under CC BY-SA 4.0; changes were made. https://creativecommons.org/licenses/by-sa/4.0/

Facts
Classification
Statement Form
Inequality 1
Connections

Has Statement Form

Inequality, 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.

Sources
1. Exterior angle theorem (Wikipedia)
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