Answer
$c \approx7.62$
$A \approx80.5^\circ$
$B\approx 29.5^\circ$
Work Step by Step
1. Use the Law of Cosines, $c=\sqrt {(8)^2+(4)^2-2(8)(4)cos70^\circ}\approx7.62$
2. Use the Law of Sines $\frac{8}{sinA}=\frac{4}{sinB}=\frac{7.62}{sin70^\circ}$
3. Thus $A=sin^{-1}(\frac{8sin70^\circ}{7.62})\approx80.5^\circ$
4. Find the third angle $B\approx180-70-80.5=29.5^\circ$
