This image was acquired from
wikimedia. It was marked as Public Domain or CC0 and is free to use. To verify, go to the source and check the information there.
Keywords from Image Description:
DegreeRadian Conversion tau.svg en chart showing the relationships between pi tau and radians with circle Shows the conversion between degrees and radians along with the signs of the major trigonometric functions in each quadrant own adapted from File DegreeRadian Conversion svg by Inductiveload DanPMK Uploaded with Units of angle