File:90 degree rotations expressed in radian measure.svg - Wikipedia

CK 12 Trigonometry Second Edition B v3 ZVD s1, PDF, Trigonometric Functions

Geometric Quantities

Turn (angle) - Wikiwand

Radian angles & quadrants (video), Radians

File:Rotation of a vector by 90 degrees.svg - Wikimedia Commons

Degree (angle) - Wikipedia

AN-1057: Using an Accelerometer for Inclination Sensing

List of trigonometric identities - Wikiwand

NetCDF Climate and Forecast (CF) Metadata Conventions

Mathematics Notes