The distance of $y$ from $A$ equals $||y-overline y||$?












1















Is the following true in $Bbb R^n$?



If $A$ is a one-dimensional subspace spanned by $u$ then for any vector $yin Bbb R^n$ the distance of $y$ from $A$ equals $||y-overline y||$
where $overline y$ is the othogonal projection of $y$ on $u$.




I know that the othogonal projection of $y$ on $u$ is $ y=frac{langle y,urangle }{langle u,urangle } u$



Also $y-overline y$ is orthogonal to $u$.



I have proved these.



But how to prove or disprove the above ?Please help










share|cite|improve this question



























    1















    Is the following true in $Bbb R^n$?



    If $A$ is a one-dimensional subspace spanned by $u$ then for any vector $yin Bbb R^n$ the distance of $y$ from $A$ equals $||y-overline y||$
    where $overline y$ is the othogonal projection of $y$ on $u$.




    I know that the othogonal projection of $y$ on $u$ is $ y=frac{langle y,urangle }{langle u,urangle } u$



    Also $y-overline y$ is orthogonal to $u$.



    I have proved these.



    But how to prove or disprove the above ?Please help










    share|cite|improve this question

























      1












      1








      1








      Is the following true in $Bbb R^n$?



      If $A$ is a one-dimensional subspace spanned by $u$ then for any vector $yin Bbb R^n$ the distance of $y$ from $A$ equals $||y-overline y||$
      where $overline y$ is the othogonal projection of $y$ on $u$.




      I know that the othogonal projection of $y$ on $u$ is $ y=frac{langle y,urangle }{langle u,urangle } u$



      Also $y-overline y$ is orthogonal to $u$.



      I have proved these.



      But how to prove or disprove the above ?Please help










      share|cite|improve this question














      Is the following true in $Bbb R^n$?



      If $A$ is a one-dimensional subspace spanned by $u$ then for any vector $yin Bbb R^n$ the distance of $y$ from $A$ equals $||y-overline y||$
      where $overline y$ is the othogonal projection of $y$ on $u$.




      I know that the othogonal projection of $y$ on $u$ is $ y=frac{langle y,urangle }{langle u,urangle } u$



      Also $y-overline y$ is orthogonal to $u$.



      I have proved these.



      But how to prove or disprove the above ?Please help







      linear-algebra geometry






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      asked Nov 29 at 15:00









      Join_PhD

      1968




      1968






















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          Hint: For any $xin A$, we have $|y-x|^2 =|y-bar y|^2+|bar y-x|^2$.






          share|cite|improve this answer





















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            Hint: For any $xin A$, we have $|y-x|^2 =|y-bar y|^2+|bar y-x|^2$.






            share|cite|improve this answer


























              0














              Hint: For any $xin A$, we have $|y-x|^2 =|y-bar y|^2+|bar y-x|^2$.






              share|cite|improve this answer
























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                Hint: For any $xin A$, we have $|y-x|^2 =|y-bar y|^2+|bar y-x|^2$.






                share|cite|improve this answer












                Hint: For any $xin A$, we have $|y-x|^2 =|y-bar y|^2+|bar y-x|^2$.







                share|cite|improve this answer












                share|cite|improve this answer



                share|cite|improve this answer










                answered Nov 29 at 15:18









                Berci

                59.4k23672




                59.4k23672






























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