1. Limited time only! Sign up for a free 30min personal 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!

Homework Help: Straightforward vector calc problem

  1. May 6, 2007 #1
    Studying for finals and I dont recall how to do projection and I don't like the explanation my textbook gives

    Problem: Find the distance from the point (1,3,-2) to the plane 2x + y - z = 1

    The answer to this problem should be sqrt(6)

    Relevant equations: ?

    The attempt at a solution:

    I know I have to do a projection of using two vectors, and I know one of the vectors is the normal vector to the plane (2i + j + k). I'm not sure how to find the other vector using the point given and which of the vectors is projected onto the other.
  2. jcsd
  3. May 6, 2007 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Welcome to the Forums,

    Well, what equation / method are you using to find the distance from the point to the plane?
  4. May 6, 2007 #3


    User Avatar
    Homework Helper

    draw a picture first....
    consider an arbitrary point P on the plane, let Q=(1,3,-2)
    now the magnitude of the proj of PQ in the direction of your normal vector IS the distance from Q to plane...
  5. May 7, 2007 #4
    ok, thanks. I got it now.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook