Chapter 8 - Applications of Trigonometric Functions - 8.3 The Law of Cosines - 8.3 Assess Your Understanding - Page 537: 4

$(a)$

$(a)$ We can find the measure of the the third angle because we know that the sum of the three angles is $180^o$. Then we can use the Law of Sines $\left(\frac{{\sin {A}}}{a} = \frac{{\sin{ B}}}{b} = \frac{{\sin {C}}}{c}\right)$ because we have one side and three angles given. Hence we can compute the rest two by the Law of Sines..