Answer
$-20.8^{\circ}$
Work Step by Step
First, ensure that your calculator is in radians.
On your graphing calculator, press the following sequence of buttons:
1. TAN$^{-1}$
2. (
3. -.3799
4. )
5. ENTER
Therefore, $tan^{-1}(-.3799)=-.363$ radians. Then, convert this number to degrees by multiplying by $\frac{180}{\pi}$.
$-.363radians=(-.363(\frac{180}{\pi}))^{\circ}\approx-20.8^{\circ}$.