




You drag the end of a 10 feet ladder along the ground at a rate of 2 ft/s.
How fast is its top along a wall descending as a function of time, given it started vertical at t_{ }=0?
x^{2} + y^{2} = 100, x = 2t until t = 5.
2xdx + 2ydy = 0
which gives the chain rule: