Derivative of tan(2x) at pi/6 without a calculator

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SUMMARY

The derivative of the function f(x) = tan(2x) at x = pi/6 can be calculated using the chain rule. The derivative f'(x) is found to be 2 * sec^2(2x). Evaluating this at x = pi/6 gives f'(pi/6) = 2 * sec^2(pi/3). Since sec(pi/3) can be expressed in terms of cosine, the final answer simplifies to 2 * (2) = 4, as sec(pi/3) = 2.

PREREQUISITES
  • Understanding of the chain rule in calculus
  • Knowledge of trigonometric functions and their derivatives
  • Familiarity with the unit circle and key angle values
  • Ability to simplify trigonometric expressions
NEXT STEPS
  • Study the chain rule in calculus for deeper understanding
  • Learn how to derive trigonometric functions, specifically secant
  • Memorize key trigonometric values for angles such as 0, pi/6, pi/4, and pi/3
  • Practice simplifying trigonometric expressions using identities
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Students studying calculus, particularly those focusing on derivatives and trigonometric functions, as well as educators looking for teaching resources on these topics.

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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?
 
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What is f'(x) ?
Hint: use the chain rule.
 
tan(pi/3) ' = sec^2(pi/3) is it??
 
And now how can you simplify that using the definition of sec?
 
SAT2400 said:

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.
SAT2400 said:

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.
 
jav said:
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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