Results 1 to 5 of 5

Math Help - Quadrilateral worded question...

  1. #1
    Junior Member
    Joined
    Nov 2008
    Posts
    34

    Quadrilateral worded question...

    ABCD is a quadrilateral with angle ABC a right angle. D lies on the perpendicular bisector of AB. The coordinates of A and B are (7, 2) and (2, 5) respectively. The equation of line AD is y=4x-26.
    I've already found the equation of the perpendicular bisector of line segment AB, which is y=5/3x-4
    a) Find the coordinates of point D.
    b) Find the gradient of line BC.
    c) Find the value of the second coordinate c of the point C(8, c).
    d) Find the area of quadrilateral ABCD.
    Thanks in advance.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Master Of Puppets
    pickslides's Avatar
    Joined
    Sep 2008
    From
    Melbourne
    Posts
    5,236
    Thanks
    28
    Quote Originally Posted by mandarep View Post
    The equation of line AD is y=4x-26.
    I've already found the equation of the perpendicular bisector of line segment AB, which is y=5/3x-4
    a) Find the coordinates of point D.
    The co0rdinates of D will be the intersection of \displaystyle y=4x-26 and \displaystyle y=\frac{5x}{3}-4 given the 2nd equation is correct. (I have not checked it, )
    Follow Math Help Forum on Facebook and Google+

  3. #3
    Junior Member
    Joined
    Nov 2008
    Posts
    34
    Thanks. I ended up getting D=(66/7, 82/7), which I think is correct.
    Do you have any idea how I find the gradient for BC, because I don't have the C coordinates.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    MHF Contributor
    Joined
    Dec 2007
    From
    Ottawa, Canada
    Posts
    3,119
    Thanks
    68
    Quote Originally Posted by mandarep View Post
    Do you have any idea how I find the gradient for BC, because I don't have the C coordinates.
    You did say this:
    "I've already found the equation of the perpendicular bisector of line segment AB, which is y=5/3x-4"
    So you know what you're doing...wonder why you're having trouble with this...
    BC has same slope as the bisector: 5/3; so using b(2,5): y intercept = 5/3;
    now C(8,c): c = (5/3)(8) + 5/3 = 15
    Follow Math Help Forum on Facebook and Google+

  5. #5
    Junior Member
    Joined
    Nov 2008
    Posts
    34
    Sorry. I guess I just didn't realize how straight forward it was.
    Thanks for getting me going on the right track.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Worded Question
    Posted in the Algebra Forum
    Replies: 3
    Last Post: September 5th 2011, 05:55 AM
  2. Worded question.
    Posted in the Algebra Forum
    Replies: 2
    Last Post: January 26th 2011, 11:54 PM
  3. [SOLVED] Easy worded question.
    Posted in the Algebra Forum
    Replies: 2
    Last Post: September 21st 2010, 11:59 AM
  4. Worded algebra question
    Posted in the Algebra Forum
    Replies: 3
    Last Post: November 30th 2009, 02:53 AM
  5. Simple Worded Question
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: July 8th 2009, 01:56 AM

Search Tags


/mathhelpforum @mathhelpforum