The general formula for the area of a triangle is A = (1)/(2) x base x height.

Here are the areas of the shaded parts for each figure:

The general formula for the area of a triangle is $A = \frac{1}{2} \times \text{base} \times \text{height}$.

i.

Step 1: Identify the base and height of the triangle.
Base $b = 4.5 \text{ cm}$
Height $h = 4 \text{ cm}$

Step 2: Apply the area formula.

$$A = \frac{1}{2} \times b \times h$$ $$A = \frac{1}{2} \times 4.5 \text{ cm} \times 4 \text{ cm}$$ $$$$