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Equation of the line joining A(-1, 9) to B(6, 12)

  1. Oct 10, 2004 #1
    1.Find the equation of the line joining A(-1, 9) to B(6, 12).
    Another line passes through C(7, -5) and meets AB at right angles at D.
    Find the equation of CD and calculate the coordinates of D.

    Given That the coordinates of M are (K, -2K) and that the distance of AM is [tex]\sqrt{178}units[/tex], calculate the value of K.

    How do i calculate the value of K?

    2. Q is the reflection of the point(2,9) in the straight line y = 2x. Calculate the coordinates of Q.
    Last edited: Oct 10, 2004
  2. jcsd
  3. Oct 10, 2004 #2
    |AM|^2=[(K+1)^2 + (-2K-9)^2] = 178 => K=2
    If Q` is the reflection of Q about the line y=2x then the line y=2x is the perpendicular bisector of QQ`. QQ` has slope = -1/2 .Find the intersection pt.
    which is the mid-pt of QQ`.

  4. Oct 10, 2004 #3
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