## Trigonometry 7th Edition

Given $b$ and $c$ and the angle between them $A$, we get the missing side : $$a^2 =b^2+c^2-2ab \cos{A}$$ We then solve for the angle that is not opposite the largest side since it has to be acute (oblique triangle has one obtuse angle at most). Assuming $c$ is the largest side, from the law of sines: $$\sin{B} = \dfrac{b \sin{A}}{a}$$