Glossary · term

Radian

Mathematics

Domain
Mathematics

Definition

The natural measure of angle: arc length divided by radius, so a full turn is 2π and a straight angle π. Not a unit but a ratio, which is why sin θ ≈ θ needs no conversion factor.

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From the Glossary database in Notion, last edited 2026-08-18. This page is the row, rendered by the build; nothing on it is written by hand.