Solving the equation we have:
[tex]\begin{gathered} \cos x=-\frac{3}{7} \\ x=\cos ^{-1}(-\frac{3}{7}) \\ x=64.62 \end{gathered}[/tex]Since the cosine function has a period of 360, this means that in the given interval, the only angle that will satisfy this condition is 64.62°.
