Yes, that's right
"?" is the adjacent and 1.3 miles is the opposite
cosine is a ratio of adjacent over hypotenuse. We have a triangle where, for the given angle, the opposite side is known and the adjacent side is unknown. One of the trig functions whose ratio contains the opposite and the adjacent is
(BTW, what's the other trig function?)
So we use the tangent ratio to find the adjacent side ( = x):
EDIT: beaten to it again!