Problema Solution
A person 6 feet tall standing 18 feet away from a lamppost cast a 9 foot shadow. When the same person moves 4 feet farther from the lamppost, he will cast a shadow how long?
Answer provided by our tutors
let
h = the height of the lamppost
s = the length of the shadow
make a good drawing and notice the similar right triangles to form the proportion:
h : 6 = (18 + 9) : 9
by solving we find:
h = 18 ft
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since we now know the height of the lamppost we make another drawing and use again the similar right triangles to form the proportion:
18 : 6 = (18 + 4 + s) : s
by solving we find:
s = 11 ft
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he will cast a shadow 9 feet long.