A fish is reeled in at a rate of 1 foot per second from a bridge 15 feet above the water. At what rate is the angle between the line and the water changing when 25 feet of line is out? (Assume the fish stays near the surface of the water.)

Answer 1

draw a diagram. If x feet of line are out,

15/x = sinθ
-15/x^2 dx/dt = cosθ dθ/dt

Now just plug in your numbers.