show that the height of the cylinder of maximum volume that can be inscribed within a cone of height $h$ is...












0












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show that the height of the cylinder of maximum volume that can be inscribed within a cone of height $h$ is $frac{h}3$.



I have tried solving this sum but am unable to substitute the radius of the cylinder in terms of $h$.










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  • $begingroup$
    See this for finding the maximum volume of a cylinder in a cone of height $h$.
    $endgroup$
    – heather
    Mar 19 '17 at 13:03
















0












$begingroup$


show that the height of the cylinder of maximum volume that can be inscribed within a cone of height $h$ is $frac{h}3$.



I have tried solving this sum but am unable to substitute the radius of the cylinder in terms of $h$.










share|cite|improve this question











$endgroup$












  • $begingroup$
    See this for finding the maximum volume of a cylinder in a cone of height $h$.
    $endgroup$
    – heather
    Mar 19 '17 at 13:03














0












0








0





$begingroup$


show that the height of the cylinder of maximum volume that can be inscribed within a cone of height $h$ is $frac{h}3$.



I have tried solving this sum but am unable to substitute the radius of the cylinder in terms of $h$.










share|cite|improve this question











$endgroup$




show that the height of the cylinder of maximum volume that can be inscribed within a cone of height $h$ is $frac{h}3$.



I have tried solving this sum but am unable to substitute the radius of the cylinder in terms of $h$.







derivatives maxima-minima






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edited Nov 27 '17 at 21:02









Siong Thye Goh

104k1468120




104k1468120










asked Mar 19 '17 at 12:40









Dhruv RaghunathDhruv Raghunath

156412




156412












  • $begingroup$
    See this for finding the maximum volume of a cylinder in a cone of height $h$.
    $endgroup$
    – heather
    Mar 19 '17 at 13:03


















  • $begingroup$
    See this for finding the maximum volume of a cylinder in a cone of height $h$.
    $endgroup$
    – heather
    Mar 19 '17 at 13:03
















$begingroup$
See this for finding the maximum volume of a cylinder in a cone of height $h$.
$endgroup$
– heather
Mar 19 '17 at 13:03




$begingroup$
See this for finding the maximum volume of a cylinder in a cone of height $h$.
$endgroup$
– heather
Mar 19 '17 at 13:03










1 Answer
1






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$begingroup$

Hint:



enter image description here



Look at the figure. With:
$$
BH=h quad HC=R quad FG=x quad HG=r
$$



from the similarity of the triangles $BHC$ and $FGC$ we have:



$$
h:x=R:(R-r)
$$
so that $r=frac{R}{h}(h-x)$



Now you can express the volume of the cylinder as $V=pi r^2x=pi frac{R^2}{h^2}(h-x)^2x $.



Maximize this function.






share|cite|improve this answer









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    1 Answer
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    active

    oldest

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    1 Answer
    1






    active

    oldest

    votes









    active

    oldest

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    active

    oldest

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    0












    $begingroup$

    Hint:



    enter image description here



    Look at the figure. With:
    $$
    BH=h quad HC=R quad FG=x quad HG=r
    $$



    from the similarity of the triangles $BHC$ and $FGC$ we have:



    $$
    h:x=R:(R-r)
    $$
    so that $r=frac{R}{h}(h-x)$



    Now you can express the volume of the cylinder as $V=pi r^2x=pi frac{R^2}{h^2}(h-x)^2x $.



    Maximize this function.






    share|cite|improve this answer









    $endgroup$


















      0












      $begingroup$

      Hint:



      enter image description here



      Look at the figure. With:
      $$
      BH=h quad HC=R quad FG=x quad HG=r
      $$



      from the similarity of the triangles $BHC$ and $FGC$ we have:



      $$
      h:x=R:(R-r)
      $$
      so that $r=frac{R}{h}(h-x)$



      Now you can express the volume of the cylinder as $V=pi r^2x=pi frac{R^2}{h^2}(h-x)^2x $.



      Maximize this function.






      share|cite|improve this answer









      $endgroup$
















        0












        0








        0





        $begingroup$

        Hint:



        enter image description here



        Look at the figure. With:
        $$
        BH=h quad HC=R quad FG=x quad HG=r
        $$



        from the similarity of the triangles $BHC$ and $FGC$ we have:



        $$
        h:x=R:(R-r)
        $$
        so that $r=frac{R}{h}(h-x)$



        Now you can express the volume of the cylinder as $V=pi r^2x=pi frac{R^2}{h^2}(h-x)^2x $.



        Maximize this function.






        share|cite|improve this answer









        $endgroup$



        Hint:



        enter image description here



        Look at the figure. With:
        $$
        BH=h quad HC=R quad FG=x quad HG=r
        $$



        from the similarity of the triangles $BHC$ and $FGC$ we have:



        $$
        h:x=R:(R-r)
        $$
        so that $r=frac{R}{h}(h-x)$



        Now you can express the volume of the cylinder as $V=pi r^2x=pi frac{R^2}{h^2}(h-x)^2x $.



        Maximize this function.







        share|cite|improve this answer












        share|cite|improve this answer



        share|cite|improve this answer










        answered Mar 19 '17 at 13:46









        Emilio NovatiEmilio Novati

        52.2k43574




        52.2k43574






























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