contestada

A cone is inscribed in a regular square pyramid. If the pyramid has a base edge of 6" and a slant height of 9", find the volume of the cone.

Respuesta :

v=(1/3)hpir²

ok, so inscribed
therefor the edge length is the diameter of the cone (the base is on bottom)
so then d=6
d/2=r
6/2=3=r


height
we need pythagoran theorem to find this
if we look at one side and draw the height then we get a right triangle with height is one leg
3 is another
and 9 is hyptonuse
a²+b²=c²
3²+h²=9²
9+h²=81
h²=72
h=6√2



h=6√2
r=3


V=(1/3)(6√2)(pi)(3²)
V=18pi√2 cubic feet

Answer:

The volume of the cone is  equal to

[tex]V=18 \pi \sqrt{2}\ in^{3}[/tex]

Step-by-step explanation:

we know that

The volume of a cone is equal to

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

where

r is the radius of the base

h is the height of the cone

In this problem the length of the square base of the pyramid is equal to the diameter of the base of the cone

so

[tex]r=6/2=3\ in[/tex]

Step 1

Find the height of the cone

Applying the Pythagoras Theorem

[tex]l^{2}=r^{2}+h^{2}[/tex]

where

l is the slant height

in this problem we have

[tex]l=9\ in[/tex]

[tex]r=3\ in[/tex]

Solve for h

[tex]h^{2}=l^{2}-r^{2}[/tex]

substitute the values

[tex]h^{2}=9^{2}-3^{2}[/tex]

[tex]h^{2}=72[/tex]

[tex]h=6\sqrt{2}\ in[/tex]

Step 2

Find the volume of the cone

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

we have

[tex]r=3\ in[/tex]

[tex]h=6\sqrt{2}\ in[/tex]

substitute the values

[tex]V=\frac{1}{3} \pi 3^{2}(6\sqrt{2})[/tex]

[tex]V=18 \pi \sqrt{2}\ in^{3}[/tex]