How do you use the quotient rule to find the derivative of X?

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Discussion Overview

The discussion revolves around finding the derivative of the function X = (cos@)/(sin@) using the quotient rule. Participants explore various approaches to differentiate this trigonometric function, including the application of derivative rules and the necessity of memorizing certain derivatives.

Discussion Character

  • Technical explanation
  • Mathematical reasoning
  • Debate/contested

Main Points Raised

  • One participant asks how to take the derivative of X = (cos@)/(sin@) and seeks clarification on dx/d@.
  • Another suggests recognizing that cosine over sine reduces to a known function, implying a simplification may help in differentiation.
  • There is a question about whether one must memorize the derivative of cotangent, indicating uncertainty about the necessity of memorization versus understanding derivative methods.
  • A participant emphasizes the importance of knowing all derivative methods to avoid re-deriving them each time, suggesting that familiarity will develop through study.
  • One participant proposes using either the product rule or the quotient rule for differentiation.
  • A question arises regarding the derivative of cotangent, with a participant asserting it equals csc squared, which is met with a suggestion to derive it to verify.
  • Another participant offers to guide the derivation process, starting with the definition of cotangent as cos(x)/sin(x) and prompting the use of the quotient rule.
  • A later reply provides the formula for the quotient rule, specifying the functions involved in the context of the discussion.

Areas of Agreement / Disagreement

Participants express varying opinions on whether to memorize derivatives or understand the underlying methods. There is no consensus on the best approach to take when differentiating the function, and the discussion remains unresolved regarding the necessity of memorization versus application of derivative rules.

Contextual Notes

Some participants assume familiarity with derivative rules and trigonometric functions, while others express uncertainty about starting points for derivation. The discussion does not resolve the correctness of the derivative claims made.

Maxwellkid
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How do u tak the derivative of

X = (cos@)/(sin@)
dx/d@ = ?
 
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Two suggestions:

first: regardless of the variable name, what function does cosine over sine reduce to?

second: use ordinary derivative tools for trig functions
 


must I merely memorize the derivate of cotangent?
 


Maxwellkid said:
must I merely memorize the derivate of cotangent?

Well, you should know how to use ALL of the derivative methods you encounter, so you don't have to re-derive them each time you need them. On the plus side: if you take enough math courses learning them will be natural. Good luck in your studies...
 


Use the product rule or the quotient rule.
 


Isn't derivative of cotangent equal to csc squared?
 


Why don't you try deriving it to check ;-)
 


Where do i start to derive it?
 


Alright, I'll start you off . . .

cot(x) = \frac{cos(x)}{sin(x)}[/itex]<br /> <br /> \frac{d(cot(x))}{dx} = \frac{d}{dx} \left (\frac{cos(x)}{sin(x)} \right )<br /> <br /> Now, can you remember the rule for differentiating the quotient of two functions?
 
  • #10


Try checking using the quotient rule:

\left({f \over g}\right)&#039; = {f&#039;g - fg&#039; \over g^2}, \qquad g \ne 0

In your case f=cos@ and g=sin@

Regards.
 

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