Answer
The length of the train is approximately 200 m
Work Step by Step
We can express the angle in degrees:
$\theta = 3^{\circ}20' = (3 + \frac{20}{60})^{\circ} = 3.33^{\circ}$
We can convert the angle to radians:
$\theta = (3.33^{\circ})(\frac{\pi~rad}{180^{\circ}}) = 0.05812~rad$
We can approximate the length $L$ of the train:
$L \approx \theta ~r$
$L \approx (0.05812~rad)(3.5~km)$
$L \approx 0.20~km$
$L \approx 200~m$
The length of the train is approximately 200 m.
