The given diagram is a traingle with base 12 units, height 4 units, and one side 9 units.
Since base (b) and height (h) are known, we can use the following formula for the area (A) of the triangle,
[tex]A=\frac{1}{2}bh[/tex]
Substitute the values and simplify the expression,
[tex]\begin{gathered} A=\frac{1}{2}\times12\times4 \\ A=6\times4 \\ A=24 \end{gathered}[/tex]
Thus, the area of the given triangle is 24 square units.
