Differentiation-rate of chang

1. A tennis player 1.8 m tall dashes at a rate of 4 m/s towards a fllod light post which is 5 m high. Find the rate of change of
(a) the displacement of the tip of his shadow,
(b) the length of his shadow.


2. In a railway station, a train, starting at noon, travels east at 75 km/h. Another train, starting at 1 p.m., travels north at 80 km/h.
(a) Find the distance between the trains at t p.m. for t > 1 or t = 1.
(b) How fast are they separating at 2 p.m.?