Conical Cups Related Rates











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Conical Paper Cup



My teacher provided the solution and I don't want to just copy it down.



I know we have V=$frac{pi r^2h}{3}$ and $dh/dt = 2$.
What I don't understand is how V=$frac{pi r^2h}{3}$ becomes V=$frac{pi h^3}{3}$. If someone could explain that to me, I will really appreciate it.



Thanks in advance!










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    up vote
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    down vote

    favorite












    Conical Paper Cup



    My teacher provided the solution and I don't want to just copy it down.



    I know we have V=$frac{pi r^2h}{3}$ and $dh/dt = 2$.
    What I don't understand is how V=$frac{pi r^2h}{3}$ becomes V=$frac{pi h^3}{3}$. If someone could explain that to me, I will really appreciate it.



    Thanks in advance!










    share|cite|improve this question


























      up vote
      0
      down vote

      favorite









      up vote
      0
      down vote

      favorite











      Conical Paper Cup



      My teacher provided the solution and I don't want to just copy it down.



      I know we have V=$frac{pi r^2h}{3}$ and $dh/dt = 2$.
      What I don't understand is how V=$frac{pi r^2h}{3}$ becomes V=$frac{pi h^3}{3}$. If someone could explain that to me, I will really appreciate it.



      Thanks in advance!










      share|cite|improve this question















      Conical Paper Cup



      My teacher provided the solution and I don't want to just copy it down.



      I know we have V=$frac{pi r^2h}{3}$ and $dh/dt = 2$.
      What I don't understand is how V=$frac{pi r^2h}{3}$ becomes V=$frac{pi h^3}{3}$. If someone could explain that to me, I will really appreciate it.



      Thanks in advance!







      calculus geometry






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      edited Nov 20 at 15:23









      Andrei

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      10.7k21025










      asked Nov 20 at 14:58









      Lola

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      156






















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          At the top $r=h=10$ cm. By using similar triangles, you have that $r=h$ at all heights. In general, you would need to write $r$ in terms of $h$, no matter the shape of the cone. In this case is trivial.






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            accepted










            At the top $r=h=10$ cm. By using similar triangles, you have that $r=h$ at all heights. In general, you would need to write $r$ in terms of $h$, no matter the shape of the cone. In this case is trivial.






            share|cite|improve this answer

























              up vote
              1
              down vote



              accepted










              At the top $r=h=10$ cm. By using similar triangles, you have that $r=h$ at all heights. In general, you would need to write $r$ in terms of $h$, no matter the shape of the cone. In this case is trivial.






              share|cite|improve this answer























                up vote
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                down vote



                accepted







                up vote
                1
                down vote



                accepted






                At the top $r=h=10$ cm. By using similar triangles, you have that $r=h$ at all heights. In general, you would need to write $r$ in terms of $h$, no matter the shape of the cone. In this case is trivial.






                share|cite|improve this answer












                At the top $r=h=10$ cm. By using similar triangles, you have that $r=h$ at all heights. In general, you would need to write $r$ in terms of $h$, no matter the shape of the cone. In this case is trivial.







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                answered Nov 20 at 15:21









                Andrei

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