在下面的长方形中，求阴影三角形的面积。

1. Identify the base and height of the shaded triangle

The shaded triangle has its base on the top edge of the rectangle. The length of this base is given as $9\text{ cm}$. The height of the triangle corresponds to the height of the rectangle, which is $8\text{ cm}$.

2. Calculate the area of the shaded triangle

$\text{Area} = \frac{1}{2} \times \text{base} \times \text{height}$
$\text{Area} = \frac{1}{2} \times 9 \times 8 = 36\text{ cm}^2$