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Math Help - Trig

  1. #1
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    Trig

    Hi, I'm after some help please.

    heres the question I've been given:

    An observer sees a ship from the top of a cliff of height 100m. The ship is seen through an instrument which measured the angle of depression to be 80o. The observer then moved back a distance of 10m, at which point the ship and the top of the cliff were in line. Find the distance from the base of the cliff to the ship.

    thanks in advance
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  2. #2
    MHF Contributor
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    Talking

    I think you'd need the height of the observer, so you could find the angle of depression from the second position...?
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  3. #3
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    the observer is at 100m.
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  4. #4
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    The cliff is 100 meters high. How tall is the observer?
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  5. #5
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    e^(i*pi)'s Avatar
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    Quote Originally Posted by stapel View Post
    The cliff is 100 meters high. How tall is the observer?
    You could probably assume that the observers height is negligible compared to the cliff height
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  6. #6
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    Quote Originally Posted by e^(i*pi) View Post
    You could probably assume that the observers height is negligible compared to the cliff height

    yea, just assume the observer is at the same height as the hill, 100m
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  7. #7
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    is this the correct diagram of ur problem?

    the angle of depression now decreases in the second triangle
    so, u can use tan to find the rest
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