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Find all solutions of sin on the interval

  1. Nov 13, 2013 #1
    1. The problem statement, all variables and given/known data

    i have

    solve 7sin(2x)-13sin(x)=0
    for all solutions 0≤X<2p
    I used the double angle formula for sin(2x)=2sin(x)cos(x)


    3. The attempt at a solution

    I'm getting stuck near the end
    7(2sin(x)cos(x)-13sin(x))
    14sin(x)cos(x)-13sin(x)

    now im stuck
     
  2. jcsd
  3. Nov 13, 2013 #2

    Curious3141

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    Homework Helper

    What you wrote aren't equations. An equation must have two sides separated by an '='. In this case, your right hand side (RHS) equals 0.

    In that final equation, can you find a common factor between the two terms?
     
  4. Nov 13, 2013 #3
    That is what i am trying ot figure out. I would just say sin(x) could be factored out.

    the 14sin and the 13sin are just throwing me off.
     
    Last edited: Nov 13, 2013
  5. Nov 13, 2013 #4
    Yep that was it. found the solutions. it was sin(x) that was the common factor. sin(x)=0 and cos(x)=13/14

    x= pi, 0 .3801 and 5.902
     
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