[tex]\bf \textit{volume of a pyramid}\\\\
V=\cfrac{Bh}{3}\qquad
\begin{cases}
B=\textit{area of its base}\\
h=height\\
----------\\
B=\stackrel{square~pyramid}{length\cdot width}\\
\qquad s\cdot s\\
\qquad s^2\\
h=\frac{2}{3}s
\end{cases}\implies V=\cfrac{s^2\cdot \frac{2s}{3}}{3}
\\\\\\
V=\cfrac{\frac{2s^3}{3}}{3}\implies V=\cfrac{\frac{2s^3}{3}}{\frac{3}{1}}\implies V=\cfrac{2s^3}{3}\cdot \cfrac{1}{3}\implies V=\cfrac{2s^3}{9}[/tex]
