Alright, well, I'm not sure if I did this the way you were supposed to, but...
I made equations for the locations of both the runner and the water.
For the runner, his x position: x = 31680-17t, and his y position: y = 5000.
Since the water forms a circle, the equation of which is x^2+y^2 =...
Why isn't it?
If line AD is congruent to line BE, doesn't that mean they are the same line, so then any two pair of lines made of those letters (line AB, line AD, line AE, line BD, line BE, line DE) are also describing the same line and thus congruent? Am I missing something?
It looks like you're trying to put the coefficient out front into the exponent, like saying 3*(x^1/2) = x^3/2, which it is not. With derivatives that coefficient just kinda stays put...