rhombus; diamond shape
Geometric term for a quadrilateral with equal sides but not necessarily right angles. Often used in mathematics; in everyday contexts, 菱形 (ひしがた) is more common.
See also: 菱形
Do you remember the formula for finding the area of a rhombus?
Square; a rhombus with right angles.
Formed from 斜方, “oblique direction or form,” and 形, “shape.” In geometry, 方形 can denote a quadrilateral as well as a square.