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Homework Help: Quadric surfaces?

  1. Sep 21, 2005 #1
    why are they called quadric surfaces?
     
  2. jcsd
  3. Sep 21, 2005 #2
    well the definition in my book gives:

    Q quadric surface is the graph of a second-degree equation in three variables x, y, and z. So i guess cause its the graph of a quadratic equation in 3-D.
     
  4. Sep 23, 2005 #3
    I have that too but i don't think the teacher would give such an easy question. thanks a bunch.
     
  5. Sep 23, 2005 #4

    HallsofIvy

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    Science Advisor

    Why are "quadratic equation" called "quadratic" when "quad" means 4?

    Apparently because a square has 4 sides!

    Extends, then to "quadric" surfaces, surfaces whose equations involve 2 nd power.
     
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