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phat2107
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Homework Statement
A street light is at the top of a 18 ft tall pole. A woman 6 ft tall walks away from the pole with a speed of 8 ft/sec along a straight path. How fast is the tip of her shadow moving when she is 30 ft from the base of the pole?
Homework Equations
http://imageiso.com/out.php/i26481_Relatedrates.JPG
18/x = 6(x-y)
The Attempt at a Solution
y=30 ft
simplified 12x=18y
tip of shadow will be at 45 ft
d/dt 12x = d/dt 18y
dx/dt 12 = dy/dt 18
if i plug the 8ft/s as my dx/dt i get a dy/dt of 16/3ft/s
but that can't be the right answer since i didnt use the 30ft given in my original question
where am i going astray?
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