Results 1 to 7 of 7

Math Help - Mid point of a line segment

  1. #1
    Junior Member
    Joined
    Oct 2007
    Posts
    52

    Mid point of a line segment

    This is the question I am trying to solve:

    A circle has centre (-1,8). If a diameter is GH and G=(3,-2), calculate the coordinates of H.

    I drew a circle with the centre as (-1,8) and G as a point on the circle as (3,-2) but I don't know what to do next.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Senior Member nikhil's Avatar
    Joined
    Jun 2008
    Posts
    290
    Hi!paulo1913.
    Here is the solution.
    Centre of the circle will be the midpoint of GH. Let coordinate of H be (x,y) then
    (3+x)/2=-1
    solving it we get x=-5
    similarly (-2+y)/2=8
    solving this we get y=18
    hence the coordinate of H are (-5,18)
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Jen
    Jen is offline
    Member Jen's Avatar
    Joined
    Feb 2008
    From
    Corvallis, Oregon
    Posts
    157
    Quote Originally Posted by Paulo1913 View Post
    This is the question I am trying to solve:

    A circle has centre (-1,8). If a diameter is GH and G=(3,-2), calculate the coordinates of H.

    I drew a circle with the centre as (-1,8) and G as a point on the circle as (3,-2) but I don't know what to do next.

    Mid point of a line segment-capture.jpg

    I know you said you already drew a picture but I think that this image might help. Consider the slope.

    Hope this helps.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Junior Member
    Joined
    Oct 2007
    Posts
    52
    Thank you very much for the help. Could you help me with this question?

    Show that the midpoint of the line segment joining (6,-1) and (-3,8) lies on the line y=-5x+11

    I figured out that the coordanates are (1.5,3.5) but I am not sure how that helps show the equation....
    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 Paulo1913 View Post
    Thank you very much for the help. Could you help me with this question?

    Show that the midpoint of the line segment joining (6,-1) and (-3,8) lies on the line y=-5x+11

    I figured out that the coordanates are (1.5,3.5) but I am not sure how that helps show the equation....
    New and unrelated questions require new threads.

    Substitute x = 1.5 into the equation for the line. Do you get y = 3.5 ....
    Follow Math Help Forum on Facebook and Google+

  6. #6
    Junior Member
    Joined
    Oct 2007
    Posts
    52
    Is that all that is required to prove that it lies on the line?
    Follow Math Help Forum on Facebook and Google+

  7. #7
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by Paulo1913 View Post
    Is that all that is required to prove that it lies on the line?
    Yes.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 1
    Last Post: June 1st 2011, 06:10 AM
  2. Replies: 0
    Last Post: January 25th 2011, 03:06 PM
  3. Replies: 2
    Last Post: June 8th 2010, 04:59 PM
  4. Replies: 8
    Last Post: March 17th 2010, 10:50 AM
  5. Vectors and point on the line segment.. (3d)
    Posted in the Calculus Forum
    Replies: 3
    Last Post: December 11th 2008, 04:02 AM

Search Tags


/mathhelpforum @mathhelpforum