360 miles would be the hypotenuse of our right triangle. 7°50' would be our angle A. Since we are looking for the base of this triangle. We will be using the cosine function.
First, we need to derive the formula for the adjacent or the base of the triangle since that is the unknown. The formula would be:
Substituting the given,
Subtracting the answer from the needed 1,400 miles we get 1,043.36 miles.