To calculate the area of a trapezium, the formula we use is:

$\text{Area} = \frac{1}{2} \times (a + b) \times h$

Where:

• $a$ and $b$ are the lengths of the two parallel sides.
• $h$ is the height (the perpendicular distance between the parallel sides).

From the image:

• One parallel side ($a$) is 18 cm.
• The other parallel side ($b$) is 10 cm.
• The height ($h$) is 20 cm.

Substituting these values into the formula:

$\text{Area} = \frac{1}{2} \times (18 + 10) \times 20$ $\text{Area} = \frac{1}{2} \times 28 \times 20$ $\text{Area} = \frac{1}{2} \times 560 = 280 \, \text{cm}^2$

Therefore, the area of the trapezium is 280 cm².

Would you like further clarification on any step, or do you have additional questions about trapeziums or other shapes?

Here are some related questions you may find interesting:

1. How can you calculate the area of a triangle?
2. What is the difference between a trapezium and a parallelogram?
3. How do you find the perimeter of a trapezium?
4. Can the formula for the area of a trapezium be used for other polygons?
5. What is the relationship between the area of a trapezium and the area of a rectangle?

Tip: When calculating areas, make sure that the units of measurement for all dimensions are consistent to avoid errors in your final result.