Stage 18 · Circles

18.3.2 The Inscribed Angle Theorem: Half the Central Angle

18.3 The Inscribed Angle Theorem — Seeing the World from On the Circle

Point 2 of 5

18.3.2 The Inscribed Angle Theorem: Half the Central Angle

Core idea

For one and the same arc, the angle you see standing on the circle is always half the angle you see standing at the center — inscribed angle = central angle ÷ 2.

Module goal. Introduce the inscribed angle, with its vertex on the circle, and establish its half relationship with the central angle plus a run of corollaries — this is the heart of the stage.
eastmath.com · 18.3 The Inscribed Angle Theorem — Seeing the World from On the Circle · 18.3.2 The Inscribed Angle Theorem: Half the Central Angle