Question

A 15-ft ladder rests against a vertical wall. If the top of the ladder slides down the wall at a rate of 0.33 ft/sec, how fast, in ft/sec, is the bottom of the ladder sliding away from the wall, at the instant when the bottom of the ladder is 9 ft from the wall? Answer with 2 decimal places.

Answer 1

we have

x^2+y^2 = 225
2x dx/dt + 2y dy/dt = 0

Now plug in x=9, y=12, dy/dt=-1/3

Answer 2

0.44