The formula to obtain the volume of the cone is
[tex]V=\frac{1}{3}\pi r^2h[/tex]where r is the radius and h is the height
in our case d is two times the radius
r=4/2=2mm
h=8mm
we substitute the values in the formula
[tex]V=\frac{1}{3}\pi(2)^2(8)=33.51\operatorname{mm}^3[/tex]