As a thought, I'd say that you need to know how far D and LA are apart in km. If the q doesn't give you that, then it's presumably down to a map, or some other such way of working out their separation distance. Once you've got that distance, and assume that it's a horizontal distance, then you' ve got a right angled triangle. in "normal" trigonometry, it would tan angle = opposite/adjacent. But for small angles, tan angle is approx equal to the angle, I think, as with the sine of a small angle.
