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Homework Help: Equation of a sphere

  1. Sep 2, 2009 #1
    1. The problem statement, all variables and given/known data
    Find an equation of the sphere with center (1,-4,3); with radius 5.
    What is the intersection of this sphere with the xz-plane?

    3. The attempt at a solution

    I am not sure what the second part of the equations is asking about, but the equation
    of the sphere is (x-1)^2 + (y+4)^2 + (z-3)^2 = 5^2.

    Any help on what the second part is about.
  2. jcsd
  3. Sep 2, 2009 #2
    You are asked to find the points on the xz-plane (y=0) where the sphere "cuts through" this plane.

    For example, a line intersects a plane at the point where it passes through it.
  4. Sep 2, 2009 #3
    So is it just the top left side of the sphere? How would I go about finding the answer?
  5. Sep 2, 2009 #4


    Staff: Mentor

    espen180 gave you a hint by telling you the equation of the x-z plane.
  6. Sep 3, 2009 #5


    User Avatar
    Science Advisor

    Since, as espen180 said, the xz-plane is defined by y= 0, replace y with 0.
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