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Equation of spere

  1. May 4, 2009 #1
    1. The problem statement, all variables and given/known data
    this problem has 3 parts

    a- Determine an equation of the spere tha passes throught th epint 6,-2,3 and has center -1,2,1
    b- Determine the curve in which this sphere intersects the yz plane
    c- Determine the center and radius of the sphere x^2 + y^2 + z^2 - 8x + 2y + 6z + 1 = 0


    2. Relevant equations



    3. The attempt at a solution

    a - r^2 = (6+1)^2 + (-2-2)^2 + (3-1)^2 = 69
    (x+1)^2 + (y-2)^2 + (z-1)^2 = 69 is this corect

    b - i dont really understand what the question is asking

    c - center is (4,-1,-3)
    r = (-1 + (8^2 + 2^2 + 6^2)/4)^1/2 = 5 is this correct
     
  2. jcsd
  3. May 4, 2009 #2

    Mark44

    Staff: Mentor

    a -- looks good
    c -- looks good

    For b, the y-z plane is the plane x = 0. You have the equation of the sphere, so just set x = 0 in that equation.
     
  4. May 4, 2009 #3
    sooooo....

    1 + (y-2)2 + (z-1)2 = 69
     
  5. May 5, 2009 #4

    Mark44

    Staff: Mentor

    Works for me.
     
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