Results 1 to 11 of 11

Math Help - Write Using Rectangular Coordinates

  1. #1
    MHF Contributor
    Joined
    Jul 2008
    From
    NYC
    Posts
    1,489

    Write Using Rectangular Coordinates

    The letters r and theta represent polar coordinates. Write each equation using rectangular coordinates (x,y).

    (1) y = 4

    (2) r = [3]/[3 - cos(theta)]
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by magentarita View Post
    The letters r and theta represent polar coordinates. Write each equation using rectangular coordinates (x,y).

    (1) y = 4

    (2) r = [3]/[3 - cos(theta)]
    (1) is already expressed in rectangular coordinates.

    (2) \Rightarrow 3r - r \cos \theta = 3.

    Substitute x = r \cos \theta and r = \sqrt{x^2 + y^2}.
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor
    Joined
    Jul 2008
    From
    NYC
    Posts
    1,489

    sorry

    Quote Originally Posted by mr fantastic View Post
    (1) is already expressed in rectangular coordinates.

    (2) \Rightarrow 3r - r \cos \theta = 3.

    Substitute x = r \cos \theta and r = \sqrt{x^2 + y^2}.
    Sorry, the first question should be r = 4 not y = 4.

    Can you show me now?
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Joined
    Jul 2008
    From
    NYC
    Posts
    1,489

    Also...

    The letters r and theta represent polar coordinates. Write each equation using rectangular coordinates (x,y).

    The second question is a fraction.


    (2) r = [3] divided by [3 - cos(theta)]
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by magentarita View Post
    The letters r and theta represent polar coordinates. Write each equation using rectangular coordinates (x,y).

    The second question is a fraction.

    (2) r = [3] divided by [3 - cos(theta)]
    I realise that. The symbol => means 'it follows that'. Do you see how what I posted follows from the second question.
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by magentarita View Post
    Sorry, the first question should be r = 4 not y = 4.

    Can you show me now?
    r = 4 => r^2 = 16. Make the obvious substitution.
    Follow Math Help Forum on Facebook and Google+

  7. #7
    MHF Contributor
    Joined
    Jul 2008
    From
    NYC
    Posts
    1,489

    I don't....

    Quote Originally Posted by mr fantastic View Post
    r = 4 => r^2 = 16. Make the obvious substitution.
    I don't see the obvious substitution.

    Please, explain.
    Follow Math Help Forum on Facebook and Google+

  8. #8
    o_O
    o_O is offline
    Primero Espada
    o_O's Avatar
    Joined
    Mar 2008
    From
    Canada
    Posts
    1,407
    You should recall that r^2 = x^2 + y^2 which should remind you of a circle
    Follow Math Help Forum on Facebook and Google+

  9. #9
    MHF Contributor
    Joined
    Jul 2008
    From
    NYC
    Posts
    1,489

    ok

    Quote Originally Posted by o_O View Post
    You should recall that r^2 = x^2 + y^2 which should remind you of a circle
    Our teacher did not teach this to the class.
    Follow Math Help Forum on Facebook and Google+

  10. #10
    o_O
    o_O is offline
    Primero Espada
    o_O's Avatar
    Joined
    Mar 2008
    From
    Canada
    Posts
    1,407
    This link should help you out: Polar Coordinates
    Follow Math Help Forum on Facebook and Google+

  11. #11
    MHF Contributor
    Joined
    Jul 2008
    From
    NYC
    Posts
    1,489

    great website

    Quote Originally Posted by o_O View Post
    This link should help you out: Polar Coordinates
    This is a great website. I've seen it before.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Polar and Rectangular Coordinates Please?
    Posted in the Pre-Calculus Forum
    Replies: 1
    Last Post: May 2nd 2010, 02:09 PM
  2. Replies: 1
    Last Post: April 23rd 2010, 11:26 AM
  3. rectangular coordinates
    Posted in the Trigonometry Forum
    Replies: 9
    Last Post: December 8th 2009, 06:24 PM
  4. Replies: 6
    Last Post: February 4th 2009, 12:12 AM
  5. Rectangular Coordinates
    Posted in the Trigonometry Forum
    Replies: 2
    Last Post: February 16th 2007, 11:02 AM

Search Tags


/mathhelpforum @mathhelpforum