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Homework Help: Dot product

  1. Mar 19, 2013 #1
    R <x,y,z>

    Show that (r-a).(r-b)=0 represents a sphere find its center and radius

    So i see that if 2 vectors are orthogonal you can create a sphere and find the radius and center but can somone better explain this problem
  2. jcsd
  3. Mar 19, 2013 #2


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    Science Advisor
    Homework Helper
    Gold Member

    What is there to explain? Write out the equations and put them in standard form to identify it. Geometrically, you may recall that an angle inscribed in a semicircle is a right angle. This is the 3D analogue of that.
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