Strange differentiation

  • #1
malawi_glenn
Science Advisor
Homework Helper
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This is a problem and i show you my work, what i dont understad is how to differentiate things like:

d(cos(t)) / dp

attachment.php?attachmentid=9995&stc=1&d=1178475756.jpg


is all i have done so far madness? or where iam i doing wrong?

(i did not got the answer myself)
 

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Answers and Replies

  • #2
cristo
Staff Emeritus
Science Advisor
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I can't see your attachment (it's not been approved yet) but to perform that derivative, you use the chain rule. So
[tex]\frac{d}{dp}(\cos t)=-\sin t\frac{dt}{dp}[/tex]
 
  • #3
HallsofIvy
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In the attachment, you are also given that p= A/2 sin t so that t= arcsin(2p/A)

You calculation looks correct except that you have forgotten the "-": d(cos(t))/dt= - sin(t) so -sin(arcsin(2p/A)= -2p/A.
 
  • #4
1,227
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HallsofIvy,

It is a bit frustating that you had the possibility to read the attachement and give a comment on it, while other members have not yet been able to read it because it is "pending".
 
Last edited:

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