Answer
$a \approx2.99$
$B \approx 19.2^\circ$
$C\approx 80.8^\circ$
Work Step by Step
1. Use the Law of Cosines, we have $a=\sqrt {(3)^2+(1)^2-2(3)(1)cos80^\circ}\approx2.99$
2. Use the Law of Sines, $\frac{sinB}{1}=\frac{sin80^\circ}{2.99}$, thus $B=sin^{-1}(\frac{sin80^\circ}{2.99})\approx 19.2^\circ$
3. We have $C\approx(180-80-19.2)=80.8^\circ$
