make a sketch.
let the length of the man's shadow be x
let the distance between the man and the post be y
by ratios:
1.7/x = 5/(x+y)
1.7x + 1.7y = 5x
1.7y = 3.3x
17y = 33x
17 dy/dt = 33 dx/dt
given: dy/dx = 2.9
33 dx/dt = 17(2.9)
dx/dt = 17(2.9)/33 = appr 1.5 m/s
notice that his shadow is lengthening at a constant rate, and it does not depend on where he is in relation to the post.
int)
A man of height 1.7 meters walk away from a 5-meter lamppost at a speed of 2.9 m/s. Find the rate at which his shadow is increasing in length.
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