- #1
QuarkCharmer
- 1,051
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Homework Statement
Differentiate:
y= u(a cos(u) + b cot(u))
Homework Equations
No Chain Rule
The Attempt at a Solution
I started out finding the derivative of (a cosu + b cotu)
I'm guessing that a/b is constant?
[tex]\frac{d}{du}(a cos(u) + b cot(u))=[/tex]
[tex]=(0(cosu)+a(-sinu))+(0(cosu)+b(-csc^2u))[/tex]
[tex]=(0+a(-sinu))+(0+b(-csc^2u))[/tex]
[tex]=(-asin(u)-bcsc^2(u))[/tex]
So then I used that and the product rule:
[tex]y'=1(a cos(u) + b cot(u))+u(-asin(u)-bcsc^2(u))[/tex]
[tex]y'=a cos(u) + b cot(u)-uasin(u)-ubcsc^2(u))[/tex]
Pretty sure I am making a huge mistake here, it doesn't feel right at all?
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