Results 1 to 5 of 5

Math Help - midpoint of a cricle.

  1. #1
    Newbie
    Joined
    Jun 2006
    Posts
    17

    midpoint of a cricle.



    Pls help me and guide me into solving this. My maths is weak so please explain to me step by step. Anyway this a a programming question. i just need steps to solve it. There is also a hint : using perpendicular line formula

    Attempt solution/what i think : Using A & B to get m1 then using perpendicular formula, to get m2(at point D). Apply same method to get m at E. so now the two mD and mE will intersect at center. From here i am lost and how to find the center coords and the radius.

    Thanks
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,969
    Thanks
    1788
    Awards
    1

    Re: midpoint of a cricle.

    Quote Originally Posted by watsonmath View Post

    There is also a hint : using perpendicular line formula
    Attempt solution/what i think : Using A & B to get m1 then using perpendicular formula, to get m2(at point D). Apply same method to get m at E. so now the two mD and mE will intersect at center. From here i am lost and how to find the center coords and the radius.
    Let A(x_a,y_a),~B(x_b,y_b),~\&~C(x_c,y_c)~.
    Then
    D:\left( {\frac{{x_a  + x_b }}{2},\frac{{y_a  + y_b }}{2}} \right)~\&~E:\left( {\frac{{x_c  + x_b }}{2},\frac{{y_c  + y_b }}{2}} \right)

    Now the slopes
    m_D=\left( { - \frac{{x_a  - x_b }}{{y_a  - y_b }}} \right)~\&~m_E=\left( { - \frac{{x_c  - x_b }}{{y_c  - y_b }}} \right).
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Newbie
    Joined
    Jun 2006
    Posts
    17

    Re: midpoint of a cricle.

    Thanks i got it. So to continue, using y = mx + c , i sub x & y of D to get c to form straight line eqn(1) likewise for E to get eqn(2).
    eqn(1) = eqn (2) Solve and substitute and i get the coordinate for center . Am i right ??


    but how can i find the radius??
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,969
    Thanks
    1788
    Awards
    1

    Re: midpoint of a cricle.

    Quote Originally Posted by watsonmath View Post
    how can i find the radius??
    If O is the center then the radius is the distance from O \text{ to }A.
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Super Member
    Joined
    Nov 2007
    From
    Trumbull Ct
    Posts
    918
    Thanks
    27

    Re: midpoint of a cricle.

    Hi watsomath,
    Without naming the coordinates A,B,C you cannot find a center coordinate or radius of the circumscribed circle
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Replies: 3
    Last Post: September 12th 2010, 03:30 AM
  2. graphing a cricle
    Posted in the Algebra Forum
    Replies: 1
    Last Post: May 3rd 2009, 03:50 PM
  3. How do you tell a cricle by the formula?
    Posted in the Math Topics Forum
    Replies: 1
    Last Post: April 26th 2009, 04:38 AM
  4. square incribed in cricle
    Posted in the Geometry Forum
    Replies: 14
    Last Post: February 7th 2009, 11:48 PM
  5. Find a Point on the Cricle
    Posted in the Geometry Forum
    Replies: 1
    Last Post: January 24th 2008, 12:12 AM

Search Tags


/mathhelpforum @mathhelpforum