a train 20ft wide is approaching an observer standing in the middle of the track at 100ft/sec.Find the rate of increase of the angle subtended by the train when the train is 20ft from the observer
I'm questioning my intuition on the problem,the way i approached this problem was through the use of $\tan{\frac{\theta}{2}}$ as it allowed me to relate the height of the triangle(the distance to the observer) and the width of the train(half of it) however i'm still in doubt about my approach and the result.