# Angle sums in triangles and polygons

Derive and use the angle sum in a triangle (180°), use it to deduce the angle sum in any polygon ((n−2) × 180°), and calculate interior and exterior angles of regular polygons

Builds on: Angles in triangles (age 10+) (hard, https://ai.page/c/angles-in-triangles-age-10/en.md), Algebraic Notation (soft, https://ai.page/c/algebraic-notation/en.md), Understanding angles (age 11+) (hard, https://ai.page/c/understanding-angles-age-11/en.md)

Concept id: angle-sums-in-triangles-and-polygons. Subject: maths. Licence: CC BY-SA 4.0.

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