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Thread: boundary

  1. #1
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    boundary

    W is the region outside of a sphere with r=5
    what is the boundary ?
    sorry this might be a silly question. i'm just debating between nothing or the sphere
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  2. #2
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    It would be useful to remember that (at least in $\displaystyle \mathbb{R}^n$) $\displaystyle \partial \Omega = \overline{ \Omega } \cap \overline{ \mathbb{R} ^n \setminus \Omega }$ ie. the boundary of a set is the same as that of it's complement.
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  3. #3
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    i'm sorry what do you mean it's compliment?
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  4. #4
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    Quote Originally Posted by calc626 View Post
    i'm sorry what do you mean it's compliment?
    If the set is $\displaystyle \Omega$ it's complemet is $\displaystyle \mathbb{R} ^n \setminus \Omega$
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  5. #5
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    so the boundary is the sphere?
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  6. #6
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    Yes
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