Related Rates... change in angle formula...

We need to find a couple of relations for this problem.

First,    and

Take the derivative of each to find the formulas for rates of change.

   and  

Using the first equation, when h=200 ft, x=173.2 ft, y=100 ft,  θ=60 degrees,
dx/dt=8 ft/sec  dy/dt=0 ft/sec  dh/dt=6.928 ft/sec

Now using the second equation dθ/dt=-.03464 degrees/second