## Algebra and Trigonometry 10th Edition

The identity is verified. $arctan(-x)=-arctan~x$
Let $x=tan~y$, then $y=arctan~x$. We know that $tan(-y)=-tan~y$ because $tan~y$ is odd. So, $-x=tan(-y)$. Then: $arctan(-x)=-y=-arctan~x$