User blog:John Lee Gamma Guild Team Vi Hart/Law of cosines/sines question???

So, I recently got the Law of cosines and Law of sines exercises to practiced. Today, I got a mastery challenge, so I tried to do it.

The direction says:

Find m\angle C m ∠ C. Note that m\angle C <span class="mord mathit" style="font-family:KaTeX_Math;font-size:inherit;font-style:italic;font-variant:inherit;font-stretch:inherit;line-height:inherit;">m <span class="mord" style="font-family:inherit;font-size:inherit;font-variant:inherit;font-stretch:inherit;line-height:inherit;">∠ <span class="mord mathit" style="margin-right:0.07153em;font-family:KaTeX_Math;font-size:inherit;font-style:italic;font-variant:inherit;font-stretch:inherit;line-height:inherit;">C     is acute. Round to the nearest degree. There's a triangle, but I don't know if I'm supposed to use the law of cosines or the law of sines to solve it!!!