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Math Help - Trig Revision

  1. #1
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    Trig Revision

    Hi

    For the question:

    An observer finds that the angle of elevation of the top of a tower from a pt A is 46 degrees. On walking 100 m closer to the ower, she finds that the angle of elevation becomes 66 degrees. Find the height of the tower to the nearest metre.

    How exactly do I start this question??

    Thanx
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  2. #2
    MHF Contributor kalagota's Avatar
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    Quote Originally Posted by xwrathbringerx View Post
    Hi

    For the question:

    An observer finds that the angle of elevation of the top of a tower from a pt A is 46 degrees. On walking 100 m closer to the ower, she finds that the angle of elevation becomes 66 degrees. Find the height of the tower to the nearest metre.

    How exactly do I start this question??

    Thanx
    draw the situation to visualize, that would be a good start..
    then, think of the ways on how you could be able to use these concepts: SOHCAHTOA, similar triangles..
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  3. #3
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    I've already drawn it but I can't seem to be able to use any of the info to find out anything useful.
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  4. #4
    MHF Contributor kalagota's Avatar
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    post what you have drawn (with the info, of course) in your next reply...
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  5. #5
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  6. #6
    MHF Contributor kalagota's Avatar
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    Quote Originally Posted by xwrathbringerx View Post
    i have expected that you would label some important points.. anyways..
    let T be the point above and O be the point on perpendicularity.. let B be the point between O and A

    let |OA| = x, |BA| = 100 so that |OB| = x-100

    using SOHCAHTOA
    |OT|=|OB|\tan(66^{\circ}) = |OA|\tan(46^{\circ})
    or
    |OT|=(x-100)\tan(66^{\circ}) = (x)\tan(46^{\circ})

    using the middle and the right side, solve for x, then substitute x to solve for |OT|..
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