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Homework Help: Plotting surfaces in 3-space

  1. Feb 23, 2015 #1
    1. The problem statement, all variables and given/known data
    Given the eqn x=2, y=sin(t), z=cos(t), draw this function in 3-space.

    2. Relevant equations
    ABOVE^

    3. The attempt at a solution
    I did this:
    x^2+y^2+z^2=2^2+(sin(t))^2+(cos(t))^2=5
    Therefore we get x^2+y^2+z^2=5
    Which is the eqn of a sphere with radius root5.

    My friend said it's supposed to be a circle but I can't see how?
    Which one of us is right if either.
     
  2. jcsd
  3. Feb 23, 2015 #2

    phyzguy

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    Science Advisor

    If x is always equal to 2, how can it be a sphere?
     
  4. Feb 23, 2015 #3
    :(
     
  5. Feb 24, 2015 #4

    haruspex

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    Gold Member

    Another way of looking at it... there is only one degree of freedom (t), so it must be a line, not a surface.
     
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