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If Dy/Dx=5, Dr/D(theta)= 18, and y=40, find theta.

  1. Sep 13, 2015 #1
    • Member warned about posting homework in a non-homework forum section
    Could anyone give me some advice as to how to solve this? P.S. Sorry if this should've gone in the Calculus forum, I didn't know which would be more appropriate.
  2. jcsd
  3. Sep 13, 2015 #2

    Simon Bridge

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    Welcome to PF;
    Lets see if I understand: you want to solve: $$\frac{dy}{dx}=5\; ;\; \frac{dr}{d\theta}=18$$ ... for ##\theta## ?

    There is not enough information ... we need to know the relationship between x y r and ##\theta##.
    If you know those, then you apply the operations to the relations and use algebra.
  4. Sep 14, 2015 #3


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    I think also that there is a problem in the request, if ##y=40## how can be possible that ## \frac{dy}{dx}=5##?
  5. Sep 14, 2015 #4
    I didn't think there was enough information either, but this was all my professor gave me and he said it is somehow possible :(
  6. Sep 18, 2015 #5

    Simon Bridge

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    @TDavenport: Context... what have the recent lessons been about?
    Maybe something about polar coordinates?

    @Ssnow: y = 5x ... dy/dx = 5 for all values of y ... but that was not the request.
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