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!

Homework Help: Convert harmonic equation to polar form

  1. Jan 15, 2008 #1


    User Avatar

    1. The problem statement, all variables and given/known data

    [tex] cos(7 t) + sin(7 t)[/tex]
    into polar form of
    [tex]A cos(\omega_0 t - \delta)[/tex]

    This is a review problem where once we convert this to polar form we are to give amplitude, period and delay (shift). I can answer this question if someone can point me to a website tutorial that tells the process of converting this problem. I really dont expect someone to answer this for me because I need to learn how to do it on my own.

    3. The attempt at a solution

    I have not made an attempt as of yet, however i know there is a trig identity
    cos(x)cos(y) + sin(x)sin(y) = cos(x-y)

    I was given this advice BUT I dont know what to do because:
    cos(7)cos(t) doesnt equal cos(7t) .... right?
    Last edited: Jan 15, 2008
  2. jcsd
  3. Jan 15, 2008 #2


    User Avatar
    Homework Helper

    Let [itex]Acos(\theta-\delta)=cos(7t)+sin(7t)[/itex] then just equate and solve
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook