Answer :
Since the diameter of the cone is 28 mm, then the radius is:
[tex]r=\frac{d}{2}=\frac{28}{2}=14\operatorname{mm}[/tex]then, we have the following equation to find the volume of the cone:
[tex]V=\frac{1}{3}\pi\cdot r^2\cdot h[/tex]in this case, we have the following information:
[tex]\begin{gathered} \pi=3.14 \\ r=14 \\ h=20 \end{gathered}[/tex]substituting these values on the equation, we have:
[tex]\begin{gathered} V=\frac{1}{3}\cdot(3.14)(14)^2(20)=\frac{1}{3}\cdot(12308.8)=4102.93 \\ V=4102.93\operatorname{mm} \end{gathered}[/tex]therefore, the volume of the cone is 4102.93mm^3