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!

Planes in 3D space

  1. Jan 7, 2007 #1
    1. The problem statement, all variables and given/known data
    Given the plane x + ky + 2z - 9 = 0, find k if the plane makes an angle of 60 degrees with the plane 2x + 2y - z = 0.


    2. Relevant equations



    3. The attempt at a solution
    I'm stumped on this question. No idea of even how to start this one.
     
  2. jcsd
  3. Jan 8, 2007 #2

    robphy

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    can you find the angle between two vectors?
     
  4. Jan 8, 2007 #3

    HallsofIvy

    User Avatar
    Staff Emeritus
    Science Advisor

    First find the normal vector for each plane- that should be easy. Then use the dot product to find the cosine of those two vectors.
     
  5. Jan 9, 2007 #4
    as hallsofIvy mentioned, the angle between two planes is the angle between their normals. Using the dot product will give you the answer,

    BUT

    your teacher might require you to actually prove that the angle between two planes is the angle between their normals. to prove this, just study the quadrilateral formed by the two planes and the two normals.
     
  6. Jan 10, 2007 #5

    robphy

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Just wondering... Are we now just giving out the solutions? We haven't even heard back from the OP.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Planes in 3D space
  1. Plane and 3d vector (Replies: 1)

Loading...