Quadrilaterals and Polygons

A polygon is any closed shape made of straight sides. A quadrilateral is a four-sided polygon. Knowing the properties tells you which one you are looking at.

• ●Square: four equal sides, four right angles.
• ●Rectangle: opposite sides equal, four right angles.
• ●Parallelogram: opposite sides parallel and equal, opposite angles equal.
• ●Trapezoid: exactly one pair of parallel sides.

Example: a quadrilateral has n = 4, so its angles add up to (4 - 2) times 180 = 360 degrees. A pentagon (n = 5) adds up to (5 - 2) times 180 = 540 degrees.

Every quadrilateral, no matter the type, has interior angles that add up to 360 degrees.