Translation guide
A four-sided shape with at least one pair of parallel sides. In US English, this is a trapezoid; in UK English, it is a trapezium. The Japanese term depends on the definition used.
The speaker is using the US definition of trapezoid, meaning a quadrilateral with at least one pair of parallel sides.
The standard Japanese term for a quadrilateral with at least one pair of parallel sides. This matches the US definition of trapezoid.
The speaker is using the UK definition of trapezoid, meaning a quadrilateral with no parallel sides. This is less common in Japanese geometry.
In US English, a trapezoid has at least one pair of parallel sides. In UK English, a trapezoid has no parallel sides. Japanese geometry follows the US definition, so 台形 (だいけい) is the standard term. Using the UK definition may cause confusion.
この図形は台形です。
This shape is a trapezoid.
A technical term for a quadrilateral with no parallel sides and all sides of different lengths. This is the closest equivalent to the UK trapezoid, but it is rarely used outside mathematical contexts.
不等辺四辺形は、どの辺も平行ではありません。
A trapezoid (UK) has no parallel sides.
Since the UK definition is not standard in Japanese, it may be clearer to describe the shape: '四辺のうち平行な辺がない四角形' (a quadrilateral with no parallel sides).
これは、平行な辺がない四角形です。
This is a quadrilateral with no parallel sides.