Question

find alpha when:

tan alpha = - 1/4

Answer 1

$\tan( \alpha ) = \frac{ - 1}{4} \\ \alpha = arc \tan( \frac{ -1 }{4} ) \\ \alpha = - arctan( \frac{1}{4} )$
any further calculation ask in comment section.

Answer 2

tan(α)=4−1​
α=arc tan(4−1​)
α=−arc tan(41​)​