The question is as follows: A rocket was launched straight up, and its altitude is given by h = 10 t2 m after t seconds. You are on the ground 300 m from the launch site watching the rocket going up. The line of sight from you to the rocket makes an angle θ with the horizontal. By how many radians per second is θ changing 10 seconds after the launch? I guess my question is whether my understanding of the problem and working is correct. I'm not 100% confident on my process and my answer and am just wondering if I have missed anything important. By working and answer is tagged below.