1. Not finding help here? Sign up for a free 30min 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!

Major h.w help needed tri functions derivatives =\

  1. Jun 27, 2007 #1
    Hey guys having major trouble with these 2 questions, i have a screen shot of the questions and my work , much easier to understand then me typing it in here. thanks soo much for helping !

    [​IMG]
     
  2. jcsd
  3. Jun 27, 2007 #2
    You have the right idea, but you just need to be watch out for a few small things.

    First of all:
    Remember the Chain Rule:
    [tex]
    \frac{d}{dx}(sin(2x)) = 2cos(2x)
    [/tex]

    Secondly:
    Be careful with your minus signs, especially with going from step 2 to step 3.

    Finally:
    Once you get all that out of the way, go through your trig identities and see if you can't simplify it any (http://www.sosmath.com/trig/Trig5/trig5/trig5.html if you need a good list of them).

    - Jason
     
  4. Jun 27, 2007 #3

    Integral

    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    You have an error in the derivitave of sin(2x) and cos(2x). Use the chain rule, you are missing a factor of 2. Continue.
     
  5. Jun 27, 2007 #4
    ok so basically for my second line i was only missing a 2 for dsin(2x)/dx and dcos(2x)/dx then i can go ahead and simplift using tri propertys? did i mix something up cause i dont see any that are obvious

    and secondly, did anyone check out the second question i had on that page, did i do the first and second derivative right?
     
  6. Jun 27, 2007 #5
    The second one matches what I got.
    CC
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?