Answer:
<u>US</u>
- 0 parallel lines
- optionally, one or two (opposite) angles may be 90°
<u>World</u>
- 2 parallel lines
- optionally, one line perpendicular to the two parallel lines
Step-by-step explanation:
It depends on where you are. A "trapezium" outside the US is the same as a "trapezoid" in the US, and vice versa.
A trapezium (World; trapezoid in the US) is characterized by exactly one pair of parallel lines. One of the lines that are not parallel may be perpendicular to the parallel lines, but that will only be true for the specific case of a "right" trapezium.
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A trapezium (US; trapezoid in the World) is characterized by no parallel lines. It <em>may</em> have one angle or opposite angles that are right angles (<em>one or two sets of perpendicular lines</em>), but neither diagonal may bisect the other.
In the US, "trapezium" is rarely used. The term "quadrilateral" is generally applied to a 4-sided figure with no sides parallel.
