List of trigonometric identities

In trigonometry, trigonometric identities are equalities that involve trigonometric functions and are true for every value of the occurring variables for which both sides of the equality are defined. Geometrically, these are identities involving certain functions of one or more angles. They are distinct from triangle identities, which are identities potentially involving angles but also involving side lengths or other lengths of a triangle.

Back to Identities & Theorems →

Source: Wikipedia · Image: Wikimedia Commons · CC BY-SA 3.0

SINCOSTAN

Trigonometry that clicks — calculators, identities, and worked explanations for angles and waves.

Get new guides by emailOccasional emails. No spam. Unsubscribe anytime.

InformationAbout Contact Privacy Policy Terms of Service Disclaimer Affiliate Disclosure Cookie Policy

Every entry, image, and fact is drawn from Wikipedia and Wikimedia Commons, used under public-domain and Creative Commons licenses. No content is AI-generated.