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!

Vector - find a

  1. Jan 26, 2010 #1
    1. Given that the two lines r1 and r2 intersect, find the value of a and hence determine the point of intersection.
    r1=i+9j-3k+landa(i+j-k)
    r2=4i+ak+mew(6i+5j+k)




    2. Relevant equations



    3. I'm a little lost with this one. Do I need to rewrite in parametric form and then cartesian form then compare i and j components. Then find values of mew and landa. Then use r1 and plug in landa value and solve for point of intersection?
     
  2. jcsd
  3. Jan 26, 2010 #2
    Using this technique I get a=-6
    and point of intersection is -52i-45j-12k

    Could somebody check this please?
     
  4. Jan 26, 2010 #3

    Mark44

    Staff: Mentor

    At a point of intersection, r1 = r2,
    so <1 + s, 9 + s, -3 -s> = <4 + 6t, 0 + 5t, a + t>
    (I have dispensed with "landa" (lambda) and "mew" (mu), and replaced them with s and t.)
    For two vectors to be equal, their corresponding components must be equal.

    The value I get for a is 78.
     
  5. Jan 27, 2010 #4
    yes thank you. I made a mistake in my layout. I have 78 now.
    and
    4i+ak-12(6i+5j+k)
    4i+78k-72i-60j-12k
    which gives -34i-30j+33k
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Vector - find a
  1. Vectors help (Replies: 5)

  2. Vector question (Replies: 2)

  3. Vectors in 3D (Replies: 2)

  4. Vectors help (Replies: 11)

Loading...