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Math Help - Bearings! please help!

  1. #1
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    Bearings! please help!

    Hey.

    From a point A on the ground, the angle of elevation to the top of a tree is 52 degrees. If the tree is 14.8m away from point A, find the height of the tree.

    The correct answer is 18.94 m

    Can anyone show me how to do this problem?


    Note: the diagram attached below is how I think it should look like based on the question.

    Thanks in advance
    Attached Thumbnails Attached Thumbnails Bearings! please help!-untitled.png  
    Last edited by fabxx; May 1st 2009 at 01:38 AM.
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  2. #2
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    Quote Originally Posted by fabxx View Post
    Hey.

    From a point A on the ground, the angle of elevation to the top of a tree is 52 degrees. If the tree is 14.8m away from point A, find the height of the tree.

    The correct answer is 18.94 m

    Can anyone show me how to do this problem?


    Note: the diagram attached below is how I think it should look like based on the question.

    Thanks in advance
    \tan(\theta) = \frac{opposite \, \,side}{adjacent \, \, side}<br />

    \tan(52) = \frac{x}{14.8}

    x = 14.8 \tan(52) = 18.9
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  3. #3
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    Quote Originally Posted by skeeter View Post
    \tan(\theta) = \frac{opposite \, \,side}{adjacent \, \, side}<br />

    \tan(52) = \frac{x}{14.8}

    x = 14.8 \tan(52) = 18.9
    But the 52 degrees is outside the triangle. Shouldn't it be 90 degrees minus 52 degrees which equal 48 degrees.

    And use tan48 to solve?

    I don't quite get it. Thanks in advance
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  4. #4
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    Quote Originally Posted by fabxx View Post
    But the 52 degrees is outside the triangle. Mr F says: No it's not. Are you familiar with the definition of angle of elevation?

    Shouldn't it be 90 degrees minus 52 degrees which equal 48 degrees.

    And use tan48 to solve?

    I don't quite get it. Thanks in advance
    Quote Originally Posted by fabxx
    the angle of elevation to the top of a tree is 52 degrees
    Regardless of how the diagram looks, angle of elevation = 52 degrees means that the 52 degrees is inside the triangle and is used as explained in post #2.
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  5. #5
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    Quote Originally Posted by fabxx View Post
    But the 52 degrees is outside the triangle. Shouldn't it be 90 degrees minus 52 degrees which equal 48 degrees.

    And use tan48 to solve?

    I don't quite get it. Thanks in advance
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