Results 1 to 2 of 2

Math Help - graph of a polar equation

  1. #1
    Newbie
    Joined
    Oct 2011
    Posts
    18

    graph of a polar equation

    How do I do this?

    Identify and graph the polar equation r=2+4cos (theta). Label three points.

    How do ifind the points basically? Thank you
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member Quacky's Avatar
    Joined
    Nov 2009
    From
    Windsor, South-East England
    Posts
    901

    Re: graph of a polar equation

    I'm assuming you want the polar plot, instead of the cartesian. Have you learned the standard forms for polar equations? This example will form a type of limašon, specifically a cardioid with an inverted loop (I'm sure this isn't the official name, but I'm afraid my vocabulary here is lacking)

    We need to know firstly where it will cut the initial line. This is where \theta=0, which is when r=6 (and this can be stated as the first point) and when \theta =\pi which is when r=-2 (second point), however we have to be cautious with the magnitude of this measurement. Because we measured from where \theta=\pi, we are measuring 2 units in the positive direction.

    This is really enough information to sketch the polar graph in my opinion, and as for the third point, just take a value for \theta and calculate the value for r.

    Using wolfram alpha gives something that looks like graph of a polar equation-cardioid.gif , which shouldn't be a surprise to you.
    Last edited by Quacky; November 17th 2011 at 05:12 AM.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Polar Graph question..
    Posted in the Calculus Forum
    Replies: 4
    Last Post: February 17th 2011, 03:41 PM
  2. Polar Graph Area
    Posted in the Calculus Forum
    Replies: 2
    Last Post: April 15th 2010, 10:50 AM
  3. 2 polar graph questions
    Posted in the Calculus Forum
    Replies: 1
    Last Post: January 21st 2010, 06:47 PM
  4. Identifying graph of a polar equation.
    Posted in the Pre-Calculus Forum
    Replies: 5
    Last Post: July 7th 2009, 11:38 PM
  5. Graph of the polar equation at the pole
    Posted in the Calculus Forum
    Replies: 2
    Last Post: May 14th 2009, 07:41 PM

Search Tags


/mathhelpforum @mathhelpforum