Understanding the Derivative of F=Fi (sin ct)

[agentnerdo]

Homework Statement

differentiate F=Fi (sin ct)

The Attempt at a Solution

Fi is a constant

= Fi (-cos ct)(c)

That is the solution I keep getting, but my buddy keeps getting

Fi (- cost ct)/c

in other words, he thinks - cost ct should be divided by c, anyone care to shed some light?

thanks in advance!

 

[╔(σ_σ)╝]

Homework Statement

differentiate F=Fi (sin ct)

The Attempt at a Solution

Fi is a constant

= Fi (-cos ct)(c)

That is the solution I keep getting, but my buddy keeps getting

Fi (- cost ct)/c

in other words, he thinks - cost ct should be divided by c, anyone care to shed some light?

thanks in advance!

Well neither of your solutions are correct. Your solution is the more "correct" of the two.

The derievative of sin(x) is cosx. You should not get a -cos(ct).Your buddy is indeed not differentiating; he is integrating.

 

[Inferior89]

Should be multiplied with c.

You are using the chain rule (f(g(x))' = f'(g(x))g'(x).
Here f(x) = F_i sin(x) and g(x) = cx.
Using the formula gives F_i cos(cx)*c

 

[Inferior89]

lol. I think you need to fix your post.



Your final formula is not correct.

Wuups... It is 4:30 AM where I live :( ...

 

[╔(σ_σ)╝]

Wuups... It is 4:30 AM where I live :( ...

You are completely excused !

I make these errors all the time. Too many times to be honest. :(

 

[agentnerdo]

thanks allot!