Question

What is the y-value for f(x) = tan(x) when x = -45°?

Answer 1

replace x by -45

Answer 2

remember:
\[\huge\rm \tan = \frac{ \sin }{ \cos }\]

Answer 3

Have you tried inputting tan(-45) into a calcualtor?

Answer 4

\(\bf tan(-45^o)=\cfrac{sin(-45^o)}{cos(-45^o)}\qquad
\begin{cases}
sin(-\theta)=-sin(\theta)\\
cos(-\theta)=cos(\theta)
\end{cases}
\\ \quad \\
\cfrac{sin(-45^o)}{cos(-45^o)}\implies \cfrac{-sin(45^o)}{cos(45^o)}\implies -\cfrac{sin(45^o)}{cos(45^o)}\implies -tan(45^o)\)

check your Unit Circle, or as suggested already, use your calculator