Differentiation 14
2011-12-15 11:15 am
A man 2 m high walks away at the rate of 2 km/h from a lamp post 3 m high. At what rate is the end of his shadow increasing its distance from the post? At what rate is his shadow lengthening?
回答 (2)
2011-12-15 7:56 pm
✔ 最佳答案
let M be the distance of man from post and S be the length of shadowby simple geometry
3/(M+S) = 2/S => S = 2M => dS/dM = 2
dM/dt = 2 (given)
dS/dt = (dS/dM) (dM/dt) = (2)(2) = 4
the rate of shadow lengthening is 4m/s
d(M+S)/dt = dM/dt + dS/dt
= 2 + 4 = 6
the rate of the shadow end increasing from the post is 6m/s
2011-12-15 7:50 pm
Any graph provided?
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useful website: http://photobucket.com/
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