Results 1 to 2 of 2

Math Help - Help with spheres - calc 3

  1. #1
    Newbie
    Joined
    Sep 2009
    Posts
    1

    Help with spheres - calc 3

    Find the equation of a sphere that contains the points (-3,0,0) (3,4,4) and (-4,3,4) if its center lies on the xz plane

    This class has just started and i have no idea where to start with this becuase this is our first homework!! I am trying to find a point equidistant from all three points that could be the center, but I could only find a place which I found to be 2z+3x=4

    Please help!! I am really frustrated =(
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Junior Member woof's Avatar
    Joined
    Apr 2009
    Posts
    31
    You probably need to know the distance formula in 3D, or the equation of a sphere, which is  (x-a)^2+(y-b)^2+(x-c)^2=r^2.

    The center on the xz plane says that the center (a, b, c)=(a, 0, c).

    Plug in the three points now and solve for a, c, and r.

    If you do not have the eqn of a sphere, you need to use the distance formula, setting up the distance between a point on the sphere (x, y, z), and the center (a, 0, c). Then substitution your three points for x, y, & z will give you three equations, with three unknowns, again a, c, and r.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Spheres Touching
    Posted in the Calculus Forum
    Replies: 4
    Last Post: September 28th 2011, 09:53 AM
  2. spheres
    Posted in the Geometry Forum
    Replies: 7
    Last Post: June 13th 2011, 05:08 PM
  3. Spheres
    Posted in the Trigonometry Forum
    Replies: 5
    Last Post: April 4th 2010, 01:03 AM
  4. Intersection of Two Spheres
    Posted in the Calculus Forum
    Replies: 6
    Last Post: January 5th 2010, 06:23 PM
  5. spheres volumes
    Posted in the Geometry Forum
    Replies: 1
    Last Post: January 14th 2009, 04:14 PM

Search Tags


/mathhelpforum @mathhelpforum