Hello!
To find the measure of side BC, we can use the trigonometric function tangent.
Tangent is opposite over adjacent. With respect to angle A which is 28 degrees, the adjacent side measure is 29.3 miles, while the opposite side is undetermined, and is what we are trying to find. Let's set up the equation.
tan(28) = x / 29.3 (multiply both sides by 29.3)
29.3tan(28) = x
x = 15.5790....
Therefore, the measure of side BC is 15.58 miles.