Calculate Parallelogram Area: 90° Right Angle with 9 and 11 Unit Measurements

To find the area of parallelogram ABCD, we will follow these steps:

• Step 1: Identify the base and height from the given diagram.
• Step 2: Apply the area formula for the parallelogram.
• Step 3: Calculate the area using the identified base and height.

Let's execute these steps:

Step 1: In parallelogram ABCD, the length of side CD is given as 11 cm. Since angle AEC is a right angle, AE, which measures 9 cm, serves as the height of the parallelogram.

Step 2: Use the formula for the area of a parallelogram:
$\text{Area} = \text{base} \times \text{height}$

Step 3: Substitute the values into the formula:
$\text{Area} = 11 \, \text{cm} \times 9 \, \text{cm} = 99 \, \text{cm}^2$

Thus, the area of the parallelogram ABCD is $\mathbf{99 \, \text{cm}^2}$.