also: だいけい
In old textbooks it is written as 梯形, but now 台形 is the usual form.
Older kanji form for 'trapezoid'; now usually written as 台形.
Modern standard spelling for 'trapezoid'.
The kanji 梯 means 'ladder' and 形 means 'shape', reflecting the trapezoid's shape. The modern form 台形 uses 台 ('platform') as a simpler substitute.