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:
Tantheta. Illustrative example as part of proof of the Routh Stability Criterion Eric Helfgott created and uploaded by en Phatom CommonsHelper Zaxxonal en diagram Zaxxonal original upload log page en Tan theta Zaxxonal bytes no GFDLself Zaxxonal bytes no to version as of March Zaxxonal bytes no Zaxxonal