A 7 ft tall person is walking away from a 20 ft tall lamppost at a rate of 5 ft/sec. Assume the scenario can be modeled with right triangles. At what rate is the length of the person's shadow changing when the person is 16 ft from the lamppost?
1 Answer
Jan 19, 2018
The length of the shadow is changing at
Explanation:
Let the distance of the person from the bottom of the light post be
And the length of his shadow is
Form the similar triangles
Differentiating wrt
We know that
Therefore,