Question

A ship is moving at a speed of 15 km/h parallel to a straight shoreline. The ship is 9 km from shore, and it passes a lighthouse at noon.
(a)
Express the distance s (in km) between the lighthouse and the ship as a function of d, the distance the ship has traveled since noon; that is, find f so that
s = f(d).

Answer 1

Since the ship is moving parallel to the shoreline, the distance s between the lighthouse and the ship is the same as the distance the ship has traveled since noon.

Therefore, the function that expresses s as a function of d is:

s = d