Hello!
The height is twice the diameter
h = 2d
The diameter is double the radius
2d = 4r
We use the equation the find the volume of a cone
[tex]V = \frac{1}{3} \pi r^{2} h[/tex]
[tex]V= \frac{1}{3} \pi r^{2} *4r[/tex]
[tex]V = \frac{4}{3} \pi r^{3} [/tex]
The answer is [tex]V = \frac{4}{3} \pi r^{3} [/tex]
Hope this helps!