Find the locus of the centroid of the triangle?












0















A plane moves so that its distance from the origin is a constant $p$. Write down the equation of the locus of the centroid of the triangle formed by its intersection with the three coordinates plane.




I was thinking about this question many times, but i could not get any hint to find the locus of the centroid of the triangle .
But i know that how to find the centroid of triangle we have to add (x+y+z/3,X+Y+Z/3), i don't know the locus of the centroid of the triangle.



if anbody help me i would be very thankful to him










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  • So the plane is always tangent to the sphere?
    – Michael Hoppe
    Aug 9 '17 at 5:53


















0















A plane moves so that its distance from the origin is a constant $p$. Write down the equation of the locus of the centroid of the triangle formed by its intersection with the three coordinates plane.




I was thinking about this question many times, but i could not get any hint to find the locus of the centroid of the triangle .
But i know that how to find the centroid of triangle we have to add (x+y+z/3,X+Y+Z/3), i don't know the locus of the centroid of the triangle.



if anbody help me i would be very thankful to him










share|cite|improve this question
























  • So the plane is always tangent to the sphere?
    – Michael Hoppe
    Aug 9 '17 at 5:53
















0












0








0








A plane moves so that its distance from the origin is a constant $p$. Write down the equation of the locus of the centroid of the triangle formed by its intersection with the three coordinates plane.




I was thinking about this question many times, but i could not get any hint to find the locus of the centroid of the triangle .
But i know that how to find the centroid of triangle we have to add (x+y+z/3,X+Y+Z/3), i don't know the locus of the centroid of the triangle.



if anbody help me i would be very thankful to him










share|cite|improve this question
















A plane moves so that its distance from the origin is a constant $p$. Write down the equation of the locus of the centroid of the triangle formed by its intersection with the three coordinates plane.




I was thinking about this question many times, but i could not get any hint to find the locus of the centroid of the triangle .
But i know that how to find the centroid of triangle we have to add (x+y+z/3,X+Y+Z/3), i don't know the locus of the centroid of the triangle.



if anbody help me i would be very thankful to him







geometry analytic-geometry locus






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edited Aug 9 '17 at 6:51









Michael Rozenberg

97.4k1589188




97.4k1589188










asked Aug 9 '17 at 5:45









lomberlomber

775320




775320












  • So the plane is always tangent to the sphere?
    – Michael Hoppe
    Aug 9 '17 at 5:53




















  • So the plane is always tangent to the sphere?
    – Michael Hoppe
    Aug 9 '17 at 5:53


















So the plane is always tangent to the sphere?
– Michael Hoppe
Aug 9 '17 at 5:53






So the plane is always tangent to the sphere?
– Michael Hoppe
Aug 9 '17 at 5:53












3 Answers
3






active

oldest

votes


















1














The equation of a variable plane in intercept form is $$frac xa+frac yb+ frac zc=1$$



Here, $a,b$ and $c$ are intercept on $x,y$ and $z$ axes.



Given, it's distance from origin is constant $$frac{Big|Big(frac xa+frac yb+ frac zc-1Big)_{x=y=z=0}Big|}{sqrt{frac {1}{a^2}+frac {1}{b^2}+frac {1}{c^2}}}=p(text{constant})$$



And centroid of triangle $$(x,y,z)=left(frac a3,frac b3,frac c3right)$$



Therefore you get $$frac{1}{p^2}=frac {1}{a^2}+frac {1}{b^2}+frac {1}{c^2}$$



Also, $a=3x,b=3y$ and $c=3z$



$$implies frac{1}{p^2}=frac {1}{9x^2}+frac {1}{9y^2}+frac {1}{9z^2}$$



Hence the desired locus is :
$$color{blue}{frac {1}{x^2}+frac {1}{y^2}+frac {1}{z^2}=frac{9}{p^2}}$$






share|cite|improve this answer























  • thanks a lot@ jaideep khare,, but i don't know where i haveto put this centroid coordinates and make a equation
    – lomber
    Aug 9 '17 at 5:57










  • What about the plane $z=p$?
    – Michael Hoppe
    Aug 9 '17 at 5:57










  • @MichaelHoppe I don't understand what you want to say.
    – Jaideep Khare
    Aug 9 '17 at 6:00










  • @lomberlego Check my edit.
    – Jaideep Khare
    Aug 9 '17 at 6:00










  • The plane given by $z=p$ doesn't have an $x$- or a $y$-intercept.
    – Michael Hoppe
    Aug 9 '17 at 6:01



















0














Let $ac+by+cz+d=0$ be an equation of the plain.



Thus, $abcneq0$ and $$frac{|d|}{sqrt{a^2+b^2+c^2}}=p,$$
which gives $$|d|=psqrt{a^2+b^2+c^2}.$$



Let $Aleft(frac{-d}{a},0,0right)$, $Bleft(0,-frac{d}{b},0right)$ and $Cleft(0,0,-frac{d}{c}right)$ and for the centroid $M$ we obtain
$$Mleft(frac{-d}{3a},frac{-d}{3b},frac{-d}{3c}right),$$
which gives
$$frac{1}{x^2}+frac{1}{y^2}+frac{1}{z^2}=frac{9(a^2+b^2+c^2)}{d^2}=frac{9}{p^2}$$






share|cite|improve this answer























  • thanks a lots @ michael Rozenberg
    – lomber
    Aug 9 '17 at 13:18










  • @lomber lego You are welcome!
    – Michael Rozenberg
    Aug 9 '17 at 14:26



















0














Let $vec s$ be a vector of length $p$. Then the plane's equation is $langlevec s,vec xrangle=p^2$. Provided that no coordinate of $vec s$ is zero, the intercepts are obviously
$$frac{p^2}{s_k}vec e_kquadtext{for $k=1,2,3$}$$
where $vec e_k$ denote the $k^text{th}$ unit vector.



The result may be easily generalized to arbitrary dimensions.






share|cite|improve this answer





















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    3 Answers
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    3 Answers
    3






    active

    oldest

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    active

    oldest

    votes






    active

    oldest

    votes









    1














    The equation of a variable plane in intercept form is $$frac xa+frac yb+ frac zc=1$$



    Here, $a,b$ and $c$ are intercept on $x,y$ and $z$ axes.



    Given, it's distance from origin is constant $$frac{Big|Big(frac xa+frac yb+ frac zc-1Big)_{x=y=z=0}Big|}{sqrt{frac {1}{a^2}+frac {1}{b^2}+frac {1}{c^2}}}=p(text{constant})$$



    And centroid of triangle $$(x,y,z)=left(frac a3,frac b3,frac c3right)$$



    Therefore you get $$frac{1}{p^2}=frac {1}{a^2}+frac {1}{b^2}+frac {1}{c^2}$$



    Also, $a=3x,b=3y$ and $c=3z$



    $$implies frac{1}{p^2}=frac {1}{9x^2}+frac {1}{9y^2}+frac {1}{9z^2}$$



    Hence the desired locus is :
    $$color{blue}{frac {1}{x^2}+frac {1}{y^2}+frac {1}{z^2}=frac{9}{p^2}}$$






    share|cite|improve this answer























    • thanks a lot@ jaideep khare,, but i don't know where i haveto put this centroid coordinates and make a equation
      – lomber
      Aug 9 '17 at 5:57










    • What about the plane $z=p$?
      – Michael Hoppe
      Aug 9 '17 at 5:57










    • @MichaelHoppe I don't understand what you want to say.
      – Jaideep Khare
      Aug 9 '17 at 6:00










    • @lomberlego Check my edit.
      – Jaideep Khare
      Aug 9 '17 at 6:00










    • The plane given by $z=p$ doesn't have an $x$- or a $y$-intercept.
      – Michael Hoppe
      Aug 9 '17 at 6:01
















    1














    The equation of a variable plane in intercept form is $$frac xa+frac yb+ frac zc=1$$



    Here, $a,b$ and $c$ are intercept on $x,y$ and $z$ axes.



    Given, it's distance from origin is constant $$frac{Big|Big(frac xa+frac yb+ frac zc-1Big)_{x=y=z=0}Big|}{sqrt{frac {1}{a^2}+frac {1}{b^2}+frac {1}{c^2}}}=p(text{constant})$$



    And centroid of triangle $$(x,y,z)=left(frac a3,frac b3,frac c3right)$$



    Therefore you get $$frac{1}{p^2}=frac {1}{a^2}+frac {1}{b^2}+frac {1}{c^2}$$



    Also, $a=3x,b=3y$ and $c=3z$



    $$implies frac{1}{p^2}=frac {1}{9x^2}+frac {1}{9y^2}+frac {1}{9z^2}$$



    Hence the desired locus is :
    $$color{blue}{frac {1}{x^2}+frac {1}{y^2}+frac {1}{z^2}=frac{9}{p^2}}$$






    share|cite|improve this answer























    • thanks a lot@ jaideep khare,, but i don't know where i haveto put this centroid coordinates and make a equation
      – lomber
      Aug 9 '17 at 5:57










    • What about the plane $z=p$?
      – Michael Hoppe
      Aug 9 '17 at 5:57










    • @MichaelHoppe I don't understand what you want to say.
      – Jaideep Khare
      Aug 9 '17 at 6:00










    • @lomberlego Check my edit.
      – Jaideep Khare
      Aug 9 '17 at 6:00










    • The plane given by $z=p$ doesn't have an $x$- or a $y$-intercept.
      – Michael Hoppe
      Aug 9 '17 at 6:01














    1












    1








    1






    The equation of a variable plane in intercept form is $$frac xa+frac yb+ frac zc=1$$



    Here, $a,b$ and $c$ are intercept on $x,y$ and $z$ axes.



    Given, it's distance from origin is constant $$frac{Big|Big(frac xa+frac yb+ frac zc-1Big)_{x=y=z=0}Big|}{sqrt{frac {1}{a^2}+frac {1}{b^2}+frac {1}{c^2}}}=p(text{constant})$$



    And centroid of triangle $$(x,y,z)=left(frac a3,frac b3,frac c3right)$$



    Therefore you get $$frac{1}{p^2}=frac {1}{a^2}+frac {1}{b^2}+frac {1}{c^2}$$



    Also, $a=3x,b=3y$ and $c=3z$



    $$implies frac{1}{p^2}=frac {1}{9x^2}+frac {1}{9y^2}+frac {1}{9z^2}$$



    Hence the desired locus is :
    $$color{blue}{frac {1}{x^2}+frac {1}{y^2}+frac {1}{z^2}=frac{9}{p^2}}$$






    share|cite|improve this answer














    The equation of a variable plane in intercept form is $$frac xa+frac yb+ frac zc=1$$



    Here, $a,b$ and $c$ are intercept on $x,y$ and $z$ axes.



    Given, it's distance from origin is constant $$frac{Big|Big(frac xa+frac yb+ frac zc-1Big)_{x=y=z=0}Big|}{sqrt{frac {1}{a^2}+frac {1}{b^2}+frac {1}{c^2}}}=p(text{constant})$$



    And centroid of triangle $$(x,y,z)=left(frac a3,frac b3,frac c3right)$$



    Therefore you get $$frac{1}{p^2}=frac {1}{a^2}+frac {1}{b^2}+frac {1}{c^2}$$



    Also, $a=3x,b=3y$ and $c=3z$



    $$implies frac{1}{p^2}=frac {1}{9x^2}+frac {1}{9y^2}+frac {1}{9z^2}$$



    Hence the desired locus is :
    $$color{blue}{frac {1}{x^2}+frac {1}{y^2}+frac {1}{z^2}=frac{9}{p^2}}$$







    share|cite|improve this answer














    share|cite|improve this answer



    share|cite|improve this answer








    edited Aug 9 '17 at 5:58

























    answered Aug 9 '17 at 5:53









    Jaideep KhareJaideep Khare

    17.7k32568




    17.7k32568












    • thanks a lot@ jaideep khare,, but i don't know where i haveto put this centroid coordinates and make a equation
      – lomber
      Aug 9 '17 at 5:57










    • What about the plane $z=p$?
      – Michael Hoppe
      Aug 9 '17 at 5:57










    • @MichaelHoppe I don't understand what you want to say.
      – Jaideep Khare
      Aug 9 '17 at 6:00










    • @lomberlego Check my edit.
      – Jaideep Khare
      Aug 9 '17 at 6:00










    • The plane given by $z=p$ doesn't have an $x$- or a $y$-intercept.
      – Michael Hoppe
      Aug 9 '17 at 6:01


















    • thanks a lot@ jaideep khare,, but i don't know where i haveto put this centroid coordinates and make a equation
      – lomber
      Aug 9 '17 at 5:57










    • What about the plane $z=p$?
      – Michael Hoppe
      Aug 9 '17 at 5:57










    • @MichaelHoppe I don't understand what you want to say.
      – Jaideep Khare
      Aug 9 '17 at 6:00










    • @lomberlego Check my edit.
      – Jaideep Khare
      Aug 9 '17 at 6:00










    • The plane given by $z=p$ doesn't have an $x$- or a $y$-intercept.
      – Michael Hoppe
      Aug 9 '17 at 6:01
















    thanks a lot@ jaideep khare,, but i don't know where i haveto put this centroid coordinates and make a equation
    – lomber
    Aug 9 '17 at 5:57




    thanks a lot@ jaideep khare,, but i don't know where i haveto put this centroid coordinates and make a equation
    – lomber
    Aug 9 '17 at 5:57












    What about the plane $z=p$?
    – Michael Hoppe
    Aug 9 '17 at 5:57




    What about the plane $z=p$?
    – Michael Hoppe
    Aug 9 '17 at 5:57












    @MichaelHoppe I don't understand what you want to say.
    – Jaideep Khare
    Aug 9 '17 at 6:00




    @MichaelHoppe I don't understand what you want to say.
    – Jaideep Khare
    Aug 9 '17 at 6:00












    @lomberlego Check my edit.
    – Jaideep Khare
    Aug 9 '17 at 6:00




    @lomberlego Check my edit.
    – Jaideep Khare
    Aug 9 '17 at 6:00












    The plane given by $z=p$ doesn't have an $x$- or a $y$-intercept.
    – Michael Hoppe
    Aug 9 '17 at 6:01




    The plane given by $z=p$ doesn't have an $x$- or a $y$-intercept.
    – Michael Hoppe
    Aug 9 '17 at 6:01











    0














    Let $ac+by+cz+d=0$ be an equation of the plain.



    Thus, $abcneq0$ and $$frac{|d|}{sqrt{a^2+b^2+c^2}}=p,$$
    which gives $$|d|=psqrt{a^2+b^2+c^2}.$$



    Let $Aleft(frac{-d}{a},0,0right)$, $Bleft(0,-frac{d}{b},0right)$ and $Cleft(0,0,-frac{d}{c}right)$ and for the centroid $M$ we obtain
    $$Mleft(frac{-d}{3a},frac{-d}{3b},frac{-d}{3c}right),$$
    which gives
    $$frac{1}{x^2}+frac{1}{y^2}+frac{1}{z^2}=frac{9(a^2+b^2+c^2)}{d^2}=frac{9}{p^2}$$






    share|cite|improve this answer























    • thanks a lots @ michael Rozenberg
      – lomber
      Aug 9 '17 at 13:18










    • @lomber lego You are welcome!
      – Michael Rozenberg
      Aug 9 '17 at 14:26
















    0














    Let $ac+by+cz+d=0$ be an equation of the plain.



    Thus, $abcneq0$ and $$frac{|d|}{sqrt{a^2+b^2+c^2}}=p,$$
    which gives $$|d|=psqrt{a^2+b^2+c^2}.$$



    Let $Aleft(frac{-d}{a},0,0right)$, $Bleft(0,-frac{d}{b},0right)$ and $Cleft(0,0,-frac{d}{c}right)$ and for the centroid $M$ we obtain
    $$Mleft(frac{-d}{3a},frac{-d}{3b},frac{-d}{3c}right),$$
    which gives
    $$frac{1}{x^2}+frac{1}{y^2}+frac{1}{z^2}=frac{9(a^2+b^2+c^2)}{d^2}=frac{9}{p^2}$$






    share|cite|improve this answer























    • thanks a lots @ michael Rozenberg
      – lomber
      Aug 9 '17 at 13:18










    • @lomber lego You are welcome!
      – Michael Rozenberg
      Aug 9 '17 at 14:26














    0












    0








    0






    Let $ac+by+cz+d=0$ be an equation of the plain.



    Thus, $abcneq0$ and $$frac{|d|}{sqrt{a^2+b^2+c^2}}=p,$$
    which gives $$|d|=psqrt{a^2+b^2+c^2}.$$



    Let $Aleft(frac{-d}{a},0,0right)$, $Bleft(0,-frac{d}{b},0right)$ and $Cleft(0,0,-frac{d}{c}right)$ and for the centroid $M$ we obtain
    $$Mleft(frac{-d}{3a},frac{-d}{3b},frac{-d}{3c}right),$$
    which gives
    $$frac{1}{x^2}+frac{1}{y^2}+frac{1}{z^2}=frac{9(a^2+b^2+c^2)}{d^2}=frac{9}{p^2}$$






    share|cite|improve this answer














    Let $ac+by+cz+d=0$ be an equation of the plain.



    Thus, $abcneq0$ and $$frac{|d|}{sqrt{a^2+b^2+c^2}}=p,$$
    which gives $$|d|=psqrt{a^2+b^2+c^2}.$$



    Let $Aleft(frac{-d}{a},0,0right)$, $Bleft(0,-frac{d}{b},0right)$ and $Cleft(0,0,-frac{d}{c}right)$ and for the centroid $M$ we obtain
    $$Mleft(frac{-d}{3a},frac{-d}{3b},frac{-d}{3c}right),$$
    which gives
    $$frac{1}{x^2}+frac{1}{y^2}+frac{1}{z^2}=frac{9(a^2+b^2+c^2)}{d^2}=frac{9}{p^2}$$







    share|cite|improve this answer














    share|cite|improve this answer



    share|cite|improve this answer








    edited Aug 9 '17 at 6:12

























    answered Aug 9 '17 at 6:04









    Michael RozenbergMichael Rozenberg

    97.4k1589188




    97.4k1589188












    • thanks a lots @ michael Rozenberg
      – lomber
      Aug 9 '17 at 13:18










    • @lomber lego You are welcome!
      – Michael Rozenberg
      Aug 9 '17 at 14:26


















    • thanks a lots @ michael Rozenberg
      – lomber
      Aug 9 '17 at 13:18










    • @lomber lego You are welcome!
      – Michael Rozenberg
      Aug 9 '17 at 14:26
















    thanks a lots @ michael Rozenberg
    – lomber
    Aug 9 '17 at 13:18




    thanks a lots @ michael Rozenberg
    – lomber
    Aug 9 '17 at 13:18












    @lomber lego You are welcome!
    – Michael Rozenberg
    Aug 9 '17 at 14:26




    @lomber lego You are welcome!
    – Michael Rozenberg
    Aug 9 '17 at 14:26











    0














    Let $vec s$ be a vector of length $p$. Then the plane's equation is $langlevec s,vec xrangle=p^2$. Provided that no coordinate of $vec s$ is zero, the intercepts are obviously
    $$frac{p^2}{s_k}vec e_kquadtext{for $k=1,2,3$}$$
    where $vec e_k$ denote the $k^text{th}$ unit vector.



    The result may be easily generalized to arbitrary dimensions.






    share|cite|improve this answer


























      0














      Let $vec s$ be a vector of length $p$. Then the plane's equation is $langlevec s,vec xrangle=p^2$. Provided that no coordinate of $vec s$ is zero, the intercepts are obviously
      $$frac{p^2}{s_k}vec e_kquadtext{for $k=1,2,3$}$$
      where $vec e_k$ denote the $k^text{th}$ unit vector.



      The result may be easily generalized to arbitrary dimensions.






      share|cite|improve this answer
























        0












        0








        0






        Let $vec s$ be a vector of length $p$. Then the plane's equation is $langlevec s,vec xrangle=p^2$. Provided that no coordinate of $vec s$ is zero, the intercepts are obviously
        $$frac{p^2}{s_k}vec e_kquadtext{for $k=1,2,3$}$$
        where $vec e_k$ denote the $k^text{th}$ unit vector.



        The result may be easily generalized to arbitrary dimensions.






        share|cite|improve this answer












        Let $vec s$ be a vector of length $p$. Then the plane's equation is $langlevec s,vec xrangle=p^2$. Provided that no coordinate of $vec s$ is zero, the intercepts are obviously
        $$frac{p^2}{s_k}vec e_kquadtext{for $k=1,2,3$}$$
        where $vec e_k$ denote the $k^text{th}$ unit vector.



        The result may be easily generalized to arbitrary dimensions.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Aug 9 '17 at 6:19









        Michael HoppeMichael Hoppe

        10.8k31834




        10.8k31834






























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