Calculate Trapezoid Area: Finding Area of ABCD with Bases 9 and 12, Height 5

To solve this problem, we'll follow these steps:

• Identify the given measurements: the lengths of the parallel sides (bases) and the height.
• Use the trapezoid area formula to calculate the area.
• Perform the necessary arithmetic to find the numerical answer.

Now, let's work through each step:
Step 1: The given measurements are $\text{Base}_1 = 9$, $\text{Base}_2 = 12$, and the height = 5.
Step 2: The formula for the area of a trapezoid is $\text{Area} = \frac{1}{2} \times (\text{Base}_1 + \text{Base}_2) \times \text{Height}$.
Step 3: Substituting the numbers into the formula, we have:
$\text{Area} = \frac{1}{2} \times (9 + 12) \times 5$

Calculating inside the parentheses first:
$9 + 12 = 21$

Then multiply by the height:
$21 \times 5 = 105$

Finally, multiply by one-half:
$\frac{1}{2} \times 105 = 52.5$

Therefore, the area of trapezoid $ABCD$ is $52.5$ .