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Math Help - Trigonometry Double Angles - 4tan(x) = 6tan(2x): Solve for x?

  1. #1
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    Trigonometry Double Angles - 4tan(x) = 6tan(2x): Solve for x?

    4tan(x) = 6 [ 2tan(x)/1 - tan2(x) ]

    Let tan(x) = a

    4a (1 - a2) = 12a
    1 - a2 = 12a/4a
    1 - a2 = 3
    therefore, a2 = -2

    Which doesn't seem right?
    Help would be appreciated, the solutions are 0, pi and 2pi

    And how do people type in that math text??!
    Thanks in advance
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  2. #2
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    Re: Trigonometry Double Angles - 4tan(x) = 6tan(2x): Solve for x?

    Here is a link to the tutorial on how to use LaTex (the math text):

    LaTex Tutorial

    I will look at your problem now.
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    Re: Trigonometry Double Angles - 4tan(x) = 6tan(2x): Solve for x?

    Thanks for the reply and the tutorial. I got the solution, which was really simple. I feel quite silly.

    0 = a3 + 2a
    0 = a (a2 + 2)
    therefore
    tan x = 0 or tan2x = -2
    x = 0, π or 2π or no solution.
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    Re: Trigonometry Double Angles - 4tan(x) = 6tan(2x): Solve for x?

    Can you help me with this one though:

    cos(2x)cos([LaTeX ERROR: Convert failed] ) + sin(2x)sin([LaTeX ERROR: Convert failed] ) = [LaTeX ERROR: Convert failed] for [0, 2[LaTeX ERROR: Convert failed]
    Last edited by iamapineapple; May 21st 2013 at 03:44 AM.
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    Re: Trigonometry Double Angles - 4tan(x) = 6tan(2x): Solve for x?

    \frac{2}{3}
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    Re: Trigonometry Double Angles - 4tan(x) = 6tan(2x): Solve for x?

    [math]\frac{1}{2}[\math]
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    Re: Trigonometry Double Angles - 4tan(x) = 6tan(2x): Solve for x?

    Okay, ignore all of that
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    Re: Trigonometry Double Angles - 4tan(x) = 6tan(2x): Solve for x?

    Quote Originally Posted by iamapineapple View Post
    [math]\frac{1}{2}[\math]
    Use / to close your brackets, not \.
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    Re: Trigonometry Double Angles - 4tan(x) = 6tan(2x): Solve for x?

    [LaTeX ERROR: Convert failed]
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    Re: Trigonometry Double Angles - 4tan(x) = 6tan(2x): Solve for x?

    y u no work
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    Re: Trigonometry Double Angles - 4tan(x) = 6tan(2x): Solve for x?

    [LaTeX ERROR: Convert failed]
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    Re: Trigonometry Double Angles - 4tan(x) = 6tan(2x): Solve for x?

    ANYWAY,
    cos(2x)cos(π/3) + sin(2x)sin(π/3) = √3/2 for [0, 2π]

    so

    1/2 cos(2x) + √3/2 sin(2x) = √3/2
    cos(2x) + √3 sin(2x) = √3
    cos(2x) + 2√3[sin(x)cos(x)] = √3

    And then I'm not sure, I tried many ways. Help would be appreciated xox
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    Re: Trigonometry Double Angles - 4tan(x) = 6tan(2x): Solve for x?

    Trigonometry Double Angles - 4tan(x) = 6tan(2x): Solve for x?-21-may-13-3.png
    Thanks from x3bnm
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  14. #14
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    Re: Trigonometry Double Angles - 4tan(x) = 6tan(2x): Solve for x?

    Quote Originally Posted by iamapineapple View Post
    y u no work
    How your mouse over this code:

    \frac{1}{2}

    There may be a problem with [math] tags. Try [tex] instead.
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    Re: Trigonometry Double Angles - 4tan(x) = 6tan(2x): Solve for x?

    \frac{1}{2}
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