1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Simplifying this derivative...

  1. Jun 27, 2017 #1
    1. The problem statement, all variables and given/known data
    Evaluate the derivative of the following function:
    f(w)= cos(sin^(-1)2w)
    2. Relevant equations
    Chain Rule
    eq0008M.gif

    3. The attempt at a solution
    I did just as the chain rule says where
    F'(w)= -[2sin(sin^(-1)2w)]/[sqrt(1-4w^(2))

    but the book gave the answer as F'(w)=(-4w)/sqrt(1-4w^(2))

    and I'm wondering if there is some kind of simplification I'm missing. Why would sin and sin^(-1) disappear?
     
  2. jcsd
  3. Jun 27, 2017 #2

    Dick

    User Avatar
    Science Advisor
    Homework Helper

    Because they are inverse functions. ##\sin(\sin^{-1}(x))=x##.
     
  4. Jun 27, 2017 #3
    Ah okay. I wasn't aware of this. Thank you.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted



Similar Discussions: Simplifying this derivative...
  1. Simplifying Derivative (Replies: 1)

Loading...