This is as much a Physics problem as it is a Trigonometry problem. It would help if you imagine a 30-60-90 triangle, with the right angle at the base of the mountain (assuming the scenario in 2 Dimensions), and the 30° angle at your feet.
Now we are given one angle and one side, and we are asked to find another side. We can use the angle and the other side to find the missing side.
Remembering the Sin, Cos, and Tan functions usage by the acronym SOH CAH TOA, we can deduce that we should use Tan for this problem, since we only do not have the Hypotenuse of the triangle.
Since tan of an angle is equal to the opposite side divided by the adjacent side, we can say that:
tan(30) = 12400/d
Where "d" is the side we are finding. We can solve for d:
d=12400/tan(30)
Since all the answer choices are rounded to the tenths' place, we should use a calculator. We find:
d=21477.4
Thus, the answer is C.
I hope this helped you, Gin. Please contact me if you need any more help or more in-depth explanations!
