1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Finding the locus, seriously need help quick

  1. Apr 2, 2009 #1
    1. Given the points A(1,4) and B(-3,2), find the equation of each locus of the pont P(x,y), a) angle APB is a right angle
    b) P is equidistant from A and the x-axu
     
  2. jcsd
  3. Apr 2, 2009 #2

    Mentallic

    User Avatar
    Homework Helper

    ok for:

    a) The key point is that it's a right angle, so simply use [tex]M_{PA}M_{PB}=-1[/tex] where M is the gradient of each line. You will end up with an equation in x and y, which is your locus.

    b) Since P is equidistant from the x-axis (y=0) and A(1,4) use the distance formula.
     
  4. Apr 2, 2009 #3
    thanks for your quick response, but could you please explain a) i seem to be having trouble i understanding the equation you have written.
     
  5. Apr 2, 2009 #4

    Mentallic

    User Avatar
    Homework Helper

    Sure, no problem.

    Are you familiar with the fact that if two lines are perpendicular to each other, their gradients multiply to give -1?

    Such as y=x and y=-x, their gradients multiplied together give: (1)(-1)=-1 and thus these lines are perpendicular (right angles) to each other.

    So [tex]M_{PA}[/tex] is the gradient of the line PA, which is found by using the gradient formula,
    [tex]\frac{y_2-y_1}{x_2-x_1}[/tex]

    If you're still unsure, just ask :smile:
     
  6. Apr 2, 2009 #5
    Thanks! That makes it a lot more clearer now. Also thanks for your fast responses. =] Hope you have a great day =]
     
  7. Apr 2, 2009 #6

    Mentallic

    User Avatar
    Homework Helper

    Glad I could help :smile: Have a great day too.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Finding the locus, seriously need help quick
  1. Need Math Help Quick! (Replies: 3)

  2. Finding the locus (Replies: 2)

Loading...