In order to find the third side of this triangle, let's use the law of the cosines:
c² = a²+b²-2.a.b.cosC
[tex]\begin{gathered} c^2=a^2+b^2-2\cdot a\cdot b\cdot\cos C \\ c^2=(5.6)^2+(10.7)^2-2\cdot5.6\cdot10.7\cdot\cos 109.3 \\ c^{2}=31.36+114.49-39.608 \\ c^{2}=106.242 \\ c=10.307 \end{gathered}[/tex]Answer: c = 10.3 km, rounded to the nearest tenth.
