I have heard about the rule of cosine, and other related rules, that someone said I may need to use in problems like this. I have never been exposed to these rules before, so I don't much know anything about them.
What tool am I supposed to use to be able to solve these type of questions? This seems really hard and time consuming for me, am I missing bits of knowledge that I supposed to know?
\begin{align} \cos \alpha &= 52/61.3 \\ \alpha &= \arccos(52/61.3) \\ & \\ \cos \beta &= 52/74.5 \\ \beta &= \arccos(52/74.5) \end{align}