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October 25, 2014

October 25, 2014

Posted by **fareha** on Sunday, December 4, 2011 at 8:06pm.

a. Find the width W at the instant the width is decreasing at the rate of .4 meters per second.

b. At what rate is the diagonal D of the rectangle changing at the instant when the width W is 10 meters?

- calculus -
**bobpursley**, Sunday, December 4, 2011 at 8:12pmlw=200

l dw/dt+ W dl/dt=0

given dl/dt=4

a) find w then dw/dt=-.4

-.4*L+W*4=0

but remember LW=200 or L=200/W

-.4*200/W+4W=0

solve for W

b. diagonal D.

D= sqrt(L^2+W^2

dD/dt= 1/2 *1/sqrt( ) * (2L dl/dt+ 2W dw/dt)

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