Results 1 to 2 of 2

Math Help - [SOLVED] comparing polar functions and graphs

  1. #1
    Junior Member
    Joined
    Apr 2009
    Posts
    41

    [SOLVED] comparing polar functions and graphs

    Using a graphing utility to see that the equations r = f_1(\theta) = 2cos(\theta) - 1 and r = f_1(\theta) = 2cos(\theta) + 1 have the same graph. Explain why. Hint show that the points (f_1(\theta + \pi), \theta + \pi) and (f_2(\theta),\theta) coincide


    f1 starts a 1 and rotates up then down. f2 starts on 3 and rotates up to the left. here is a table showing the values of f1 and f2 at four points of the graph.

    th 0, pi/2, pi, 3pi/2
    f1 1, -1, -3, -1
    f2 3, 1, -1, 1

    points of the functions for 0, pi/2, pi, 3pi/2
    (f_1(\theta + \pi), \theta + \pi) (-3,pi) (-1, 3pi/2) (1,0) (-1, pi/2)
    (f_2(\theta),\theta) (3,0) (1, pi/2) (-1, pi) (1, 3pi/2)

    these are all the same points. a negative r means flip it over to the other direction(+pi degrees). Looking at the first table f1 (1,0) and f2 (-1, pi). these are the same points. Shifting by pi results in the same points. The functions share the same points but at different input values of theta.
    Last edited by diroga; June 14th 2009 at 03:31 PM.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Junior Member
    Joined
    Apr 2009
    Posts
    41
    I re-uploaded the graph. I think I am correct on this but I would like some other insight.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Comparing Two Graphs
    Posted in the Advanced Applied Math Forum
    Replies: 0
    Last Post: May 6th 2010, 01:26 AM
  2. Replies: 4
    Last Post: March 23rd 2010, 10:52 AM
  3. comparing graphs of functions
    Posted in the Pre-Calculus Forum
    Replies: 14
    Last Post: September 22nd 2009, 09:36 PM
  4. [SOLVED] Polar graphs
    Posted in the Pre-Calculus Forum
    Replies: 4
    Last Post: June 14th 2008, 03:29 PM
  5. Polar Coordinates and Polar Graphs
    Posted in the Pre-Calculus Forum
    Replies: 4
    Last Post: October 2nd 2007, 04:44 PM

Search Tags


/mathhelpforum @mathhelpforum