圓錐體積
\[ \displaystyle \begin{aligned} &= \frac{1}{3} \times \text{底圓面積} \times \text{錐高}\\[6pt] &= \frac{1}{3} \times \text{圓周率} (\cong 3.1415926) × \text{半徑}^2 × \text{錐高} \\[6pt] &= \frac{1}{12} \times \text{圓周率} × \text{直徑}^2 × \text{錐高} \\[6pt] &= \frac{1}{12} \; \pi D^2 H \\[6pt] \end{aligned} \]