The Ladder Problem: Differentiation

Question:

A 25ft ladder is leaning against a vertical wall. The bottom of the ladder is pulled horizontally away from the wall at 3 ft/sec. How fast is the top of the ladder sliding down the wall when the bottom of the ladder is 15ft away from the wall?

Answer:

1a)

From the question we know that when x = 15ft, y = 20ft and dx/dt = 3ft/sec. We can input this data into our derived formula.

The top of the ladder is sliding down the wall at the rate of 9/4 ft/sec.