78
From the figure 
Let us consider a triangle ABC with medians AD, BE, and CF.
The medians of a triangle intersect at a point called the centroid, denoted by G.
Key Property: The centroid divides each median in the ratio 2:1, with the longer segment being from vertex to centroid.
The centroid divides median \( AD \) in the ratio \( 2:1 \):
\[ GD = \frac{1}{3} \times AD = \frac{1}{3} \times 12 = 4 \]
Similarly, centroid divides median \( BE \) in the ratio \( 2:1 \):
\[ GB = \frac{2}{3} \times BE = \frac{2}{3} \times 9 = 6 \]
\[ \text{Area}_{\triangle BGD} = \frac{1}{2} \times GB \times GD = \frac{1}{2} \times 6 \times 4 = 12 \]
It is a well-known geometric result that all three medians divide triangle \( ABC \) into six smaller triangles of equal area.
Hence, the total area is: \[ \text{Area}_{\triangle ABC} = 6 \times \text{Area}_{\triangle BGD} = 6 \times 12 = \boxed{72} \]

For any natural number $k$, let $a_k = 3^k$. The smallest natural number $m$ for which \[ (a_1)^1 \times (a_2)^2 \times \dots \times (a_{20})^{20} \;<\; a_{21} \times a_{22} \times \dots \times a_{20+m} \] is: