Quadrilateral
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A quadrilateral is a four-sided polygon.
Quadrilateral is an elementary-school-level concept. It is listed in the California State Standards for Grade 3.
Examples
| Parallelogram: | A parallelogram is a quadrilateral with opposite sides parallel and therefore opposite angles equal. |
| Rectangle: | A rectangle is a quadrilateral with opposite sides of equal length and with four right angles. |
| Square: | A square is a polygon with four sides of equal length and at right angles to each other. |