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Calculus(f(x)= tan(2x)

  • Thread starter SAT2400
  • Start date
  • #1
69
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Homework Statement



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

Homework Equations



deriv. of tan(pi/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?
 

Answers and Replies

  • #2
259
2
What is f'(x) ?
Hint: use the chain rule.
 
  • #3
69
0
tan(pi/3) ' = sec^2(pi/3) is it??
 
  • #4
jav
35
0
And now how can you simplify that using the definition of sec?
 
  • #5
33,507
5,192

Homework Statement



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

Homework Equations



deriv. of tan(pi/3)
The derivative of tan(pi/3) is zero. tan(pi/3) is a constant, and the derivative of any constant is zero.

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?
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.
 
  • #6
259
2
And now how can you simplify that using the definition of sec?
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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