Results 1 to 2 of 2
Like Tree1Thanks
  • 1 Post By Plato

Thread: Vector dot product question- due tomorrow, please help!!

  1. #1
    Newbie
    Joined
    Nov 2018
    From
    United Kingdom
    Posts
    1

    Vector dot product question- due tomorrow, please help!!

    2 Consider a triangle ABC and let D be a point on the line between A and B. Use thedot product to prove that|−→AC|2|−−→BD| + |−−→BC|2|−−→AD| − |−−→CD|2|−→AB| = |−→AB||−−→AD||−−→BD|.Hint: You may find it helpful to write everything in terms ofx =−−→AD, y =−−→DC, z =−−→BDusing the identities−→AC =−−→AD +−−→DC and −−→BC =−−→BD +−−→DC.
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor

    Joined
    Aug 2006
    Posts
    22,150
    Thanks
    3042
    Awards
    1

    Re: Vector dot product question- due tomorrow, please help!!

    Quote Originally Posted by TheBoy View Post
    2 Consider a triangle ABC and let D be a point on the line between A and B. Use thedot product to prove that|−→AC|2|−−→BD| + |−−→BC|2|−−→AD| − |−−→CD|2|−→AB| = |−→AB||−−→AD||−−→BD|.Hint: You may find it helpful to write everything in terms ofx =−−→AD, y =−−→DC, z =−−→BDusing the identities−→AC =−−→AD +−−→DC and −−→BC =−−→BD +−−→DC.
    Your notation is so p*** poor as to be unreadable. Here is a guess.
    You will not get help until you confirm. IS THIS CORRECT?
    $\displaystyle {\left\| {\overrightarrow {AC} } \right\|^2}\left\| {\overrightarrow {BD} } \right\| + {\left\| {\overrightarrow {BC} } \right\|^2}\left\| {\overrightarrow {AD} } \right\| - {\left\| {\overrightarrow {CD} } \right\|^2}\left\| {\overrightarrow {AB} } \right\| = \left\| {\overrightarrow {AB} } \right\|\left\| {\overrightarrow {AD} } \right\|\left\| {\overrightarrow {BD} } \right\|$
    Thanks from topsquark
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Help with cross product vector question
    Posted in the Calculus Forum
    Replies: 2
    Last Post: Jul 8th 2015, 06:00 PM
  2. Vector dot product question
    Posted in the Algebra Forum
    Replies: 5
    Last Post: Mar 11th 2013, 11:22 PM
  3. vector dot product question
    Posted in the Calculus Forum
    Replies: 8
    Last Post: Feb 2nd 2011, 02:06 PM
  4. Replies: 4
    Last Post: Feb 17th 2009, 04:33 PM
  5. Replies: 2
    Last Post: Feb 17th 2009, 04:27 PM

/mathhelpforum @mathhelpforum