a cone-shaped paper drinking cup is to be made to hold 27cm3 of water. find the height and radius of the cup that will use the smallest amount of paper.

Respuesta :

The height and radius of the cone-shaped cup that will use the smallest amount of paper, that is the maximum volume is  3.72 and  2.632 respectively.

Formula used in the solution is

Volume of the cone= (1/3)π(r^2)h

Area of the cone= πr√(l^2 + r^2)

Given, the volume of the cone is 27 cm^3.

(1/3)π(r^2)h =27

Simplifying the equation to get the value of r.

π(r^2)=81/h

r^2=81/hπ

[tex]r=\sqrt{\frac{81}{\pi h} }[/tex]

Substituting the value of r in area, we get

[tex]A=\pi \sqrt{\frac{81}{\pi h} } \sqrt{h^{2} + \frac{81}{\pi h} }[/tex]

[tex]\frac{dA}{dh} =\pi \sqrt{\frac{81}{\pi h} } \sqrt{h^{2} + \frac{81}{\pi h} }[/tex]

dA/dh=√81 × (π - 162/[tex]h^{3}[/tex]) × 1/√(πh + 81/[tex]h^{2}[/tex])

At dA/dh=0, we will get,

√81 × (π - 162/[tex]h^{3}[/tex]) × 1/√(πh + 81/[tex]h^{2}[/tex])=0

√81 × (π - 162/[tex]h^{3}[/tex])=0

[tex]\pi - \frac{162}{h^{3} }=0[/tex]

Thus, [tex]\pi h^{3} -162=0[/tex]

[tex]\pi h^{3} =162[/tex]

[tex]h^{3} =\frac{162}{\pi}[/tex]

h^3= 51.5662015618

h= 3.7221

Now, substitute h in radius,

[tex]r=\sqrt{\frac{81}{\pi \times 3.7221} }[/tex]

r=2.632

Hence, the height of the cone shaped cup is 3.7221 and the radius is 2.632.

To learn more on cone here:

https://brainly.com/question/23863102#

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