Answer:82.8 degreesStep-by-step explanation:The information given here SSS. That means side-side-side.So we get to use law of cosines.[tex](\text{ the side opposite the angle you want to find })^2=a^2+b^2-2ab \cos(\text{ the angle you want to find})[/tex]Let's enter are values in.[tex]12^2=10^2+8^2-2(10)(8) \cos(B)[/tex]I'm going to a little simplification like multiplication and exponents.[tex]144=100+64-160 \cos(B)[/tex]I'm going to some more simplification like addition.[tex]144=164-160\cos(B)[/tex]Now time for the solving part. I'm going to subtract 164 on both sides:[tex]-20=-160\cos(B)[/tex]I'm going to divide both sides by -160:[tex]\frac{-20}{-160}=\cos(B)[/tex]Simplifying left hand side fraction a little:[tex]\frac{1}{8}=\cos(B)[/tex]Now to find B since it is inside the cosine, we just have to do the inverse of cosine.That looks like one of these:[tex]\cos^{-1}( )[/tex] or [tex]\arccos( )[/tex]Pick your favorite notation there. They are the same.[tex]\cos^{-1}(\frac{1}{8})=B[/tex]To the calculator now:[tex]82.81924422=B[/tex]Round answer to nearest tenths:[tex]82.8[/tex]