Posted by **Grant** on Friday, May 3, 2013 at 8:35am.

A ladder 10 m long rests on horizontal ground and leans against a

vertical wall. The foot of the ladder is pulled away from the wall at 2

m/s. How fast is the top sliding down the wall when the foot of the

ladder is 6m from the wall?

- math -
**Reiny**, Friday, May 3, 2013 at 9:42am
x^2 + y^2 = 100 , where x is the base, y the height

2x dx/dt + 2y dy/dt = 0

given: dx/dt = 2 , and x = 6

then 36+y^2 = 100

y^2 = 64

y = 8

in

2x dx/dt + 2y dy/dt = 0

2(6)(2) + 2(8)dy/dt = 0

dy/dt = -24/16 = -3/2

it is sliding down at 3/2 m/sec

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