To calculate how far east the car travels when you know the distance and the angle from east, you can use the cosine function. In this case, the distance traveled (45 km) serves as the hypotenuse, and you want to find the adjacent side (the distance east).
The cosine function relates the adjacent side to the hypotenuse as follows:
\[ \text{adjacent} = \text{hypotenuse} \times \cos(\text{angle}) \]
Therefore, the correct answer is:
C. Since we know the hypotenuse and want to calculate the adjacent side of the given angle, we use the cosine function multiplied by the hypotenuse.