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Homework Help: Simple trig problem

  1. Jun 30, 2010 #1
    "simple" trig problem

    1. The problem statement, all variables and given/known data 2(sinA+cosB)sinB=3-cosB. Find 3tan2A+4tan2B

    2. Relevant equations Trig Identities

    3. The attempt at a solution well, i expanded 3tan2A+4tan2B= 3sin2Acos2B+4sin2Bcos2A all over cos2Acos2B after that I am stuck.
    Last edited: Jun 30, 2010
  2. jcsd
  3. Jun 30, 2010 #2
    Re: "simple" trig problem

    I didn't get you. How you expanded tan^2 A?
    How will u express tan A in terms of sin A and cos A?
  4. Jun 30, 2010 #3
    Re: "simple" trig problem

    Ok, 3tan2A= 3sin2A/cos2A and 4tan2B= 4sin2B/cos2B, so 3sin2A/cos2A+4sin2B/cos2B= 3sin2Acos2B+4sin2Bcos2A all over cos2Acos2B
  5. Jun 30, 2010 #4
    Re: "simple" trig problem

    Are you sure that one of the cosines isn't "cosA" ???
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