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Homework Help: Inverse trig function

  1. Mar 4, 2010 #1
    1. The problem statement, all variables and given/known data
    Find the exact value of the expression:

    2. Relevant equations

    3. The attempt at a solution
    I know you're supposed to use sin2x=2sinxcosx somehow but not sure how to start.
  2. jcsd
  3. Mar 4, 2010 #2


    Staff: Mentor

    Start by letting u = arcsin(3/5). Then your expression is sin(2u) = ?

    It will be helpful to draw a right triangle where u is one of the acute angles. Label the sides and hypotenuse so that sin(u) = 3/5.
  4. Mar 4, 2010 #3
    Ah, OK! 24/25 correct?
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