The question is a ladder is 10 ft long and leans against a wall. The top of the ladder slides down at 3 m/s and the bottom slides away from the wall at 4 m/s. Find how high the top of the ladder is up the wall.
I know the general solution to these problems starts with using Pythagorean's theorem but I'm confused how I start this question when I'm not given x (distance from the wall). I've tried to re-arrange Pythagorean's theorem as follows:
l^2 - x^2 = y^2 Plug into Pythagorean's theorem: l^2 = x^2 + l^2 - x^2
But that doesn't get me anywhere. I know how to do implicit differientation, so could someone explain or give a hint as to how I find x?