Question

A rope attached to a pulley is being used to tow a canoe to shore. The pulley is
mounted on a dock, and the rope is attached to the front of the canoe. The pulley
is fixed at a height of 15 feet above the water level (see diagram). At the moment
when the length of rope is decreasing at a rate of 0.52 feet per second, the canoe is
21 feet from the base of the dock.
Use calculus to determine how fast the canoe is moving through the water
at this moment.

Answer 1

I know its something with pythagorean theorem...

Answer 2

this is a rate of change problem . the reason you can't use pythagorean easily here is simply because the rope size is decreasing every second

Answer 3

What am I suppose to use?

Answer 4

ahh wait yes you do use pythagorean theorem but not in a way to find that length of the rope right away

Answer 5

yeah something with the derivative

Answer 6

but I don't know how to find the change in y

Answer 7

yep you wnt to use

\[a^2+b^2=c^2\] and take the derivative of such