Among all right circular cones with a slant height of 24​, what are the dimensions​ (radius and​ height) that maximize the volume of the​ cone? The slant height of a cone is the distance from the outer edge of the base to the vertex. Let V be the volume of the cone. What is the objective function in terms of the height of the​ cone, h?

Respuesta :

Answer:

5571.99

Step-by-step explanation:

We need to use the Pythagorean theorem to solve the problem.

The theorem indicates that,

[tex]r^2+h^2=24^2 \\r^2+h^2=576\\r^2=576-h^2[/tex]

Once this is defined, we proceed to define the volume of a cone,

[tex]v=\frac{1}{3}\pi r^2 h[/tex]

Substituting,

[tex]v=\frac{1}{3} \pi (576-h^2)h\\v=\frac{1}{3} \pi (576h-h^3)[/tex]

We need to find the maximum height, so we proceed to calculate h, by means of its derivative and equalizing 0,

[tex]\frac{dv}{dh} = \frac{1}{3} \pi (576-3h^2)[/tex]

[tex]\frac{dv}{dh} = 0[/tex] then [tex]\rightarrow \frac{1}{3}\pi(576-3h^2)=0[/tex]

[tex]h_1=-8\sqrt{3}\\h_2=8\sqrt{3}[/tex]

We select the positiv value.

We have then,

[tex]r^2 = 576-(8\sqrt3)^2 = 384\\r=\sqrt{384}[/tex]

We can now calculate the maximum volume,

[tex]V_{max}= \frac{1}{3}\pi r^2 h = \frac{1}{3}\pi (\sqrt{384})^2 (8\sqrt{3}) = 5571.99[/tex]