Results 1 to 2 of 2

Math Help - Coordinate Proof... Perpendicular Lines

  1. #1
    Junior Member
    Joined
    Nov 2010
    Posts
    57

    Coordinate Proof... Perpendicular Lines

    Prove: If the product of the slopes of two lines is -1, then the lines are perpendicular.

    I have already proven the converse of this statement. I have no idea where to go / what to do for this proof...
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    Joined
    Jun 2009
    Posts
    806
    Thanks
    4
    If θ1 and θ2 are the angles made by the two straight lines with x-axis, then the angle between the two straight line is given by
    θ= θ2 - θ1.
    Τhen tanθ = tan(θ2 - θ1) = (tanθ2 - tanθ1)/( 1 +tanθ1*tanθ2) = (m2 - m1)/(1 + m1*m2)
    If m1*m2 = -1, tanθ becomes infiifnty which is possible when θ = π/2.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Coordinate geometry and perpendicular distance
    Posted in the Pre-Calculus Forum
    Replies: 2
    Last Post: October 26th 2010, 04:03 AM
  2. perpendicular lines proof
    Posted in the Pre-Calculus Forum
    Replies: 6
    Last Post: January 20th 2010, 10:47 PM
  3. lines perpendicular
    Posted in the Calculus Forum
    Replies: 1
    Last Post: August 19th 2008, 11:28 PM
  4. Perpendicular lines
    Posted in the Calculus Forum
    Replies: 1
    Last Post: April 17th 2008, 12:51 AM
  5. Replies: 1
    Last Post: January 18th 2007, 05:18 AM

Search Tags


/mathhelpforum @mathhelpforum