Question

I need help with this practice from my trigonometry prep book I attempted this previously, struggling, I got two answers and I’m not sure if I’m correct so I would like more clarification

Answer 1

$\begin{gathered} \tan (\alpha)=-\frac{12}{5} \\ \cos (\beta)=\frac{3}{5} \end{gathered}$$\begin{gathered} \alpha=\tan ^{-1}(-\frac{12}{5})+180 \\ \beta=360-\cos ^{-1}(\frac{3}{5}) \end{gathered}$

Therefore:

$\cos (\alpha-\beta)=-\frac{63}{65}$