Answer
(a) SAS is given in the question.
(b) We should use the law of cosines to begin solving the triangle.
Work Step by Step
(a) The lengths of two sides are given and the angle between them is given. Therefore, SAS is given in the question.
(b) If we tried to use the law of sines to begin solving the triangle, we would be missing two pieces of information in the equation. So this method would not work.
We should use the law of cosines to begin solving the triangle. We should use the law of cosines to find the length of the side $a$:
$a^2 = b^2+c^2-2bc~cos~A$
$a = \sqrt{b^2+c^2-2bc~cos~A}$
