Show Quadrilateral just means "four sides" A Quadrilateral has four-sides, it is 2-dimensional (a flat shape), closed (the lines join up), and has straight sides. geometry/images/geom-quad.js?mode=choose (Also see this on Interactive Quadrilaterals) PropertiesA quadrilateral has:
Try drawing a quadrilateral, and measure the angles. They should add to 360° Types of QuadrilateralsThere are special types of quadrilateral: Some types are also included in the definition of other types! For example a square, rhombus and rectangle are also parallelograms. See below for more details. Let us look at each type in turn: The Rectanglethe little squares in each corner mean "right angle" A rectangle is a four-sided shape where every angle is a right angle (90°). Also opposite sides are parallel and of equal length. The Squarethe little squares in each corner mean "right angle" A square has equal sides (marked "s") and every angle is a right angle (90°) Also opposite sides are parallel. A square also fits the definition of a rectangle (all angles are 90°), and a rhombus (all sides are equal length). The RhombusA rhombus is a four-sided shape where all sides have equal length (marked "s"). Also opposite sides are parallel and opposite angles are equal. Another interesting thing is that the diagonals (dashed lines) meet in the middle at a right angle. In other words they "bisect" (cut in half) each other at right angles. A rhombus is sometimes called a rhomb or a diamond. The ParallelogramA parallelogram has opposite sides parallel and equal in length. Also opposite angles are equal (angles "A" are the same, and angles "B" are the same). NOTE: Squares, Rectangles and Rhombuses are all Parallelograms!
A parallelogram with:
is a square! The Trapezoid (UK: Trapezium)
A trapezoid (called a trapezium in the UK) has a pair of opposite sides parallel. And a trapezium (called a trapezoid in the UK) is a quadrilateral with NO parallel sides:
An Isosceles trapezoid, as shown above, has left and right sides of equal length that join to the base at equal angles. The KiteHey, it looks like a kite (usually). It has two pairs of sides: Each pair is made of two equal-length sides that join up. Also:
... and that's it for the special quadrilaterals. Irregular QuadrilateralsThe only regular (all sides equal and all angles equal) quadrilateral is a square. So all other quadrilaterals are irregular. The "Family Tree" ChartQuadrilateral definitions are inclusive.
So we include a square in the definition of a rectangle. (We don't say "Having all 90° angles makes it a rectangle except when all sides are equal then it is a square.") This may seem odd, as in daily life we think of a square as not being a rectangle ... but in mathematics it is. Using the chart below we can answer such questions as:
Complex QuadrilateralsOh Yes! when two sides cross over, we call it a "Complex" or "Self-Intersecting" quadrilateral, like these: They still have 4 sides, but two sides cross over. PolygonA quadrilateral is a polygon. In fact it is a 4-sided polygon, just like a triangle is a 3-sided polygon, a pentagon is a 5-sided polygon, and so on. Play with ThemNow that you know the different types, you can play with the Interactive Quadrilaterals. Other NamesA quadrilateral can sometimes be called:
621,622,623,624,763,764, 2128, 2129, 3230, 3231 Copyright © 2021 MathsIsFun.com Uh-Oh! That’s all you get for now. We would love to personalise your learning journey. Sign Up to explore more. Sign Up or Login Skip for now Uh-Oh! That’s all you get for now. We would love to personalise your learning journey. Sign Up to explore more. Sign Up or Login Skip for now
(c) kite A kite has two pairs of equal adjacent sides, but unequal opposite sides. |