The area of a trapezium is dependent on which two dimensions?

The area of a trapezium is calculated using the formula:

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

where (a) and (b) are the lengths of the two parallel sides (often referred to as the bases), and (h) is the height of the trapezium, which is the perpendicular distance between the two bases.

The correct choice identifies that the area depends on the height and the sum of the lengths of the two parallel sides. The height is crucial because it determines how "tall" the trapezium is, while the sum of the bases impacts the overall width of the trapezium we are calculating the area for.

Understanding this formula is vital because it emphasizes the geometric nature of trapeziums, showcasing how the area is a function of both vertical and horizontal dimensions through the bases and height. This relationship makes the calculation precise for determining the area enclosed by the trapezium's structure.