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Homework Help: Trigonometric Equation 2

  1. Jan 8, 2008 #1
    1. The problem statement, all variables and given/known data
    tan^2x = 2tanx*sinx

    2. Relevant equations

    3. The attempt at a solution

    tan^2x = 2tanx*sinx

    (tan^2x)/tanx = (2tanx*sinx)/tanx

    tanx = 2sinx

    sinx/cosx = 2sinx

    cosx = 1/2

    x = [tex]pi[/tex]/3

    [tex]\alpha[/tex] = [tex]pi[/tex]/3 and 5[tex]pi[/tex]/3

    Not sure what I'm doing wrong.

    The answer is [tex]pi[/tex]/3 and 5[tex]pi[/tex]/3 and 0, and [tex]pi[/tex]

    Thanks for the assistance, I greatly appreciate it.
  2. jcsd
  3. Jan 8, 2008 #2


    User Avatar
    Homework Helper

    Do not simply just divide by tanx
    Bring 2tanx*sinx onto the other side and then factor out the tanx

    Dividing by tanx implies that tanx is never equal to zero. Which it can be in this case.
  4. Jan 8, 2008 #3


    User Avatar
    Science Advisor

    Either tan2(x)/tan x= 2 tan(x) sin(x)/tan(x) or tan(x)= 0.

  5. Jan 8, 2008 #4
    Thanks for the help, rock.freak667 and HallsofIvy.

    I got it now.
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