Results 1 to 2 of 2

Math Help - Foci of Ellipse, urgent help needed

  1. #1
    Member
    Joined
    Nov 2008
    Posts
    79

    Foci of Ellipse, urgent help needed

    I need to find the Foci of this Ellipse in standard form:
    (1/25)(x - 2)^2 + (1/4)(y + 3)^2 = 1 .

    please help!
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member

    Joined
    May 2006
    From
    Lexington, MA (USA)
    Posts
    11,738
    Thanks
    644
    Hello, 14041471!

    Find the Foci of this ellipse: . \frac{(x-2)^2}{25} + \frac{(y+3)^2}{4} \:=\:1

    We see that this is a "horizontal" ellipse.
    The major axis is horizontal; the foci are to the right and left of the center.

    We see that the center is: . C(2,\text{-}3)

    From c^2 \:=\:a^2-b^2, we have: . c^2 \:=\:25-4 \:=\:21 \quad\Rightarrow\quad c \:=\:\pm\sqrt{21}


    Therefore, the foci are: . \left(2+\sqrt{21},\:\text{-}3\right)\:\text{ and }\:\left(2-\sqrt{21},\:\text{-}3\right)

    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Finding the foci of an ellipse from an equation.
    Posted in the Pre-Calculus Forum
    Replies: 3
    Last Post: February 22nd 2010, 09:03 AM
  2. Replies: 2
    Last Post: August 21st 2009, 05:13 AM
  3. The foci of an ellipse - a bit unusual
    Posted in the Geometry Forum
    Replies: 10
    Last Post: August 19th 2009, 12:57 AM
  4. Finding the coordinates of foci in an ellipse
    Posted in the Math Topics Forum
    Replies: 1
    Last Post: May 23rd 2009, 03:00 PM
  5. Need help finding foci of an ellipse
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: December 1st 2008, 12:15 PM

Search Tags


/mathhelpforum @mathhelpforum