Circumference of the base (c) = 66 m
Height of the conical tent (h) = 12 m
Radius
\[=\text{ }c/2\pi \text{ }=\text{ }66/\text{ }2\pi \text{ }=\text{ }\left( 33\text{ x }7 \right)/22\text{ }=\text{ }21/2\text{ }=\text{ }10.5\text{ }m\]
the volume of the cone tent
\[\begin{array}{*{35}{l}}
=\text{ }1/3\text{ }\pi {{r}^{2}}h \\
=\text{ }1/3\text{ x }22/7\text{ x }{{\left( 21/2 \right)}^{2}}~x\text{ }12 \\
=\text{ }1386\text{ }{{m}^{3}} \\
\end{array}\]
Therefore, the volume of air contained is 1386 m3.