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Glissando
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Homework Statement
A man 1.8m tall walks at 1.5m/s along the edge of a road which is 8m wide. A street light 6.3m high is situated on the other side of the road. How fast is the length of the man's shadow changing when he is 8m past the point on the road opposite the light?
Homework Equations
Similar triangles
The Attempt at a Solution
**I'm not sure if I have the picture correct. I drew a big right triangle with one side being 6.3 and the bottom being x and y (I don't think the 8m plays a role in this question?) and I drew a smaller triangle in side and put in 1.8m.
1.8/x = 6.3/ (x+y)
1.8x + 1.8y = 6.3x
1.8y = 4.5x
1.8dy/dx = 4.5 (1.5)
dy/dx = 3.75
The answer is supposed to be 3/(5sqrt(2))
Thank you (: