Question 197183: Shad is 3 ft. from a lamppost that is 12 ft. high. If Shad is 5 1/2 ft. tall, How long is Shad's shadow?
Answer by RAY100(1637)   (Show Source):
You can put this solution on YOUR website! A rough sketch helps to visualize.
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Large rt triangle, square corner on right, height an right is 12, other leg, horizontal, is x.
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Smaller triangle is drawn inside , with height 5.5.,,,horizontal leg is (x-3).
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horizontal difference between heights is 3
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Problem is proportional triangles, one 12 height by (x) leg,,,other 5.5 high,,(x-3) leg
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12/x = 5.5 / (x-3)
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cross multiply
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12x -36 =5.5 x
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6.5 x = 36
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x=5.54,,,,lamppost shadow lg
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Therefore Shad's shadow lg = (x-3) = 2.54
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checking
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12/5.54 = 5.5 /2.54,,,,,ok
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