The economic issue in this observation involves the concept of homogeneous and differentiated product in microeconomics
According to Lindeman (2002), product homogeneity is present when the merchandise produced by companies are equivalent, the same. Homogeneous products are also a feature of perfect competition market such as wheat, grain, cooper, etc where purchasers only shoot for the cheapest goods available for sale (Lindeman, 2002).
In our circumstance, petrol and liquefied petroleum gas are homogeneous products regardless of the petrol train station or company (BP, Shell, Caltex, etc) you are buying from. In fact, the technique to extract and refine petroleum is nearly the same among those companies.
Before getting to the question on «how to find the area of a trapezoid », first let’s figure out what a trapezoid and an area of a trapezoid are. Trapezoid is a figure with four sides, so it is a quadrilateral, because quadrilaterals are figures with four sides. However, two sides of a trapezoid are parallel and the other two sides are not. Its parallel sides are called the base of a trapezoid, and the other two are called the legs or the lateral sides. So, a trapezoid is a quadrilateral figure with one pair of parallel sides. The distance between the two bases of a trapezoid is height. Etymology of a Trapezoid The expression «trapezoid» has been in application in the English language since 1570, from Greek «trapezion» and from Late Latin trapezium, which word for word means a «small table».