Posted by **Anonymous** on Monday, November 5, 2007 at 8:58pm.

1) A ladder 25 feet long is leaning against the wall of a house. The base of the ladder is pulled away from the wall at a rate of 2 feet per second.

Find the rate at which the are of the triangle is changing when the base of the ladder is 7 feet from the wall.

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I did the Pythagorean to find the other side of the triangle and got 24. But I'm confused...am I looking for the dr/dt OR dv/dt? Or something else?

Help please!

- calculus -
**bobpursley**, Monday, November 5, 2007 at 9:04pm
Rate at which area is changing, dA/dt

where A= 1/2 b*height

dA/dt= 1/2 b dh/dt + 1/2 h db/dt

- calculus -
**bobpursley**, Monday, November 5, 2007 at 9:42pm
No. You are given db/dt

Using the pyth theorm

c^2= b^2 + h^2

dc/dt=0= 2b db/dt + 2h dh/dt

solve for dh/dt in terms of b,h, db/dt

this is what related rates means.

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