A railroad track in the desert is 3.5 km away. A train on the track subtends (horizontally) an angle of θ. Find the length of the train.
a) 3.5 km * tan(θ)
b) 3.5 km / tan(θ)
c) 3.5 km * sin(θ)
d) 3.5 km / sin(θ)