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**doctorgk** A boat is pulled into a dock by means of a winch 12 feet above the deck of the boat.

A-._

-..... _

- ........_

- ..........._

- ............._

- ................_

C-................ _B

Thats a 90 degree right triangle, the boat is at B, the winch at A, and line AC is the 12 feet.

The winch pulls in rope at a rate of 4 feet per second. there is 13 feet of rope out (line AB), f__ind the acceleration of the boat.__

okay, so i solved for line CB using the pythagorean theorem, which is 5 feet. i know i have to implicitely differentiate, then a second time because it is acceleration. could anyone help me.