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Homework Help: Calculus(f(x)= tan(2x)

  1. Mar 17, 2010 #1
    1. The problem statement, all variables and given/known data

    If f(x)= tan(2x), then f'(pi/6) =

    2. Relevant equations

    deriv. of tan(pi/3)

    3. The attempt at a solution

    How can I solve this? I am not supposed to use a calculator?? tan(pi/3) ...am I supposed to memorize this?
  2. jcsd
  3. Mar 17, 2010 #2
    What is f'(x) ?
    Hint: use the chain rule.
  4. Mar 17, 2010 #3
    tan(pi/3) ' = sec^2(pi/3) is it??
  5. Mar 17, 2010 #4


    User Avatar

    And now how can you simplify that using the definition of sec?
  6. Mar 18, 2010 #5


    Staff: Mentor

    The derivative of tan(pi/3) is zero. tan(pi/3) is a constant, and the derivative of any constant is zero.
    Yes. There are a few angles whose trig functions you should have memorized - 0, pi/6, pi/4, pi/3, pi/2, as well as their supplements and combinations with pi/2, pi, and so on. You should also have memorized all of the six trig functions in terms of the sine or cosine.
  7. Mar 18, 2010 #6
    Can you write sec x in terms of sine and/or cosine? You should have memorized the values of sin(pi/3) and cos(pi/3)
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