Understanding Differentiation: The Madness of d(cos(t))/dp

[malawi_glenn]

This is a problem and i show you my work, what i don't understad is how to differentiate things like:

d(cos(t)) / dp

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

(i did not got the answer myself)

 

[cristo]

I can't see your attachment (it's not been approved yet) but to perform that derivative, you use the chain rule. So
$$\frac{d}{dp}(\cos t)=-\sin t\frac{dt}{dp}$$

 

[HallsofIvy]

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.

 

[lalbatros]

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".