## Calculus with Applications (10th Edition)

$tan120^\circ=-1$
We are given $\tan120^\circ$ We can find the value by using right-angled triangle create by x, y, r and $\theta=60^\circ$ From the $30^\circ-60^\circ-90^\circ$ we will have $x=-1, y=1, r=1$ Using the definitions of the trigonometric functions give the following result $tan120^\circ=-1$