I am suppose to work this out somehow but I am not sure. I have tried many ways and I can't progress any further.
A streethg light his mounted at the top of a 15 ft tall pole. A man 6 ft tall walks away from the pole at a speed of 5ft/s along a straight path. How fast is the tip of the shadow moving when he is 40tf from the pole?
From this I know that I have a triangle with 2 known values on it, 15tf tall and then an opposite side of that is 6 feet tall. The rate of change of the bottom of the triangle is 5. I need to solve for c prime I am pretty sure. I am just not sure how to get that. I tried many different ways and none are correct.I tried to set up the pythagorean theorem but it didn't work and I am not sure why. I know that if I have 2 sides of a triangle I can figure out a third, so I tried to find the derivative of that but that didn't work.