Results 1 to 8 of 8

Math Help - Equations of the circle, midpoints and so on.

  1. #1
    Newbie
    Joined
    Sep 2008
    Posts
    6

    Equations of the circle, midpoints and so on.

    Hey,
    I'm pretty ok at maths however I really get stuck on the whole circle problems and would appreciate some help

    1. Part 1 - Find the mid-point, C, of AB where A is (1,8) and B is (3,14) respectively.

    Part 2 - Find the distance between AC

    Part 3 - Find the equation of the circle which has AB as diameter.

    Thanks a lot
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member 11rdc11's Avatar
    Joined
    Jul 2007
    From
    New Orleans
    Posts
    894
    midpoint

    \frac{1+3}{2}, \frac{14+8}{2}
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Sep 2008
    Posts
    6
    Ok so midpoint is 2,11 should have said I already got that but that's the easy bit.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Super Member 11rdc11's Avatar
    Joined
    Jul 2007
    From
    New Orleans
    Posts
    894
    part 2

    distance formula

    \sqrt{(2-1)^2 +(11-8)^2} =
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Newbie
    Joined
    Sep 2008
    Posts
    6
    So thats Square Root of 10 overall which is 3.16227766..and so on.
    Now the 3rd part
    Follow Math Help Forum on Facebook and Google+

  6. #6
    MHF Contributor
    Joined
    Apr 2008
    Posts
    1,092
    The distance between A and C, or the length of the line segment AC, is calculated as:

    \sqrt{(2-1)^2 + (11-8)^2}

    The circle with AB as diameter has center C, and its radius is the length of AC. The equation for a circle with center (h, k) and radius r is (x-h)^2 + (y-k)^2 = r^2. Just plug in the numbers; you've got all of them now.
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Newbie
    Joined
    Sep 2008
    Posts
    6
    Does that mean I use the vales of C for h,k so it would be as follows?

    <br />
(x-2)^2 + (y-11)^2 = r^2<br />
    Follow Math Help Forum on Facebook and Google+

  8. #8
    MHF Contributor
    Joined
    Apr 2008
    Posts
    1,092
    Yes, you use the coordinates of C for h and k.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. 3-D Coordinates & Midpoints. [HELP PLEASE]
    Posted in the Statistics Forum
    Replies: 0
    Last Post: October 17th 2010, 09:41 AM
  2. Midpoints in a Triangle
    Posted in the Geometry Forum
    Replies: 1
    Last Post: February 6th 2010, 05:52 PM
  3. Finding the midpoints and mean
    Posted in the Statistics Forum
    Replies: 1
    Last Post: September 19th 2009, 06:27 AM
  4. MidPoints
    Posted in the Geometry Forum
    Replies: 0
    Last Post: October 14th 2008, 04:48 AM
  5. Midpoints and ratios
    Posted in the Math Topics Forum
    Replies: 4
    Last Post: December 7th 2007, 11:16 PM

Search Tags


/mathhelpforum @mathhelpforum