Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: Derivative of trig functions

  1. Jan 22, 2006 #1
    I need a quick check on my math. Derivative of composite function y=sec^2(X) where X is a polynomial.
    Does it equal:
    y'=(secXtanX)(secX)(X)(dy/dx)+(secX)(secXtanX)(dy/dx)(X)+(secX)(secX)(dy/dx)

    I'm a little confused on applying the product rule and the chain rule to this function.
     
    Last edited: Jan 22, 2006
  2. jcsd
  3. Jan 22, 2006 #2
    One more question. Compostie function y=csc(x) where X is a polynomial.
    Does the first derivative of csc(X) equal:
    y'=-csc(X)cot(X)(dy/dx)?
     
    Last edited: Jan 22, 2006
  4. Jan 22, 2006 #3

    StatusX

    User Avatar
    Homework Helper

    I'm not sure what y is, but just apply the chain rule (ie, first the square, then the sec, then X).
     
  5. Jan 22, 2006 #4

    Hurkyl

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    None of those can be right, since there is no y in your problem!
     
  6. Jan 22, 2006 #5
    Ugh, stupid little things, I'll edit.
     
  7. Jan 22, 2006 #6

    Hurkyl

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    y' = dy/dx.
     
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook