Part B: First of all, domain is the set of all x-values. -3 is the smallest x-value of this graph, and since it's a closed circle, you represent it with a bracket. 5 is the largest x-value, but it's and open circle so you use a parentheses to represent it.
The side opposite the angle 19 degrees is given by 15sin 19 = 4.9 units, while the side adjacent the angle 19 degrees is given by 15cos 19 = 14.2 units.