So all other quadrilaterals are irregular. The only regular (all sides equal and all angles equal) quadrilateral is a square. and that's it for the special quadrilaterals.
one of the diagonals bisects (cuts equally in half) the other.the diagonals, shown as dashed lines above, meet at.The KiteĮach pair is made of two equal-length sides that join up. (the US and UK definitions are swapped over!)Īn Isosceles trapezoid, as shown above, has left and right sides of equal length that join to the base at equal angles. NOTE: Squares, Rectangles and Rhombuses are allĪ trapezoid (called a trapezium in the UK) has a pair of opposite sides parallel.Īnd a trapezium (called a trapezoid in the UK) is a quadrilateral with NO parallel sides:
Also opposite anglesĪre equal (angles "A" are the same, and angles "B" The ParallelogramĪ parallelogram has opposite sides parallel and equal in length. In other words they "bisect" (cut in half) each other at right angles.Ī rhombus is sometimes called a rhomb or a diamond. This would be an isosceles triangle, but its not equilateral. Here we have two sides that are the same length, but the third is different. In fact, not even two of the sides are the same length. The RhombusĪ rhombus is a four-sided shape where all sides have equal length (marked "s").Īlso opposite sides are parallel and opposite angles are equal.Īnother interesting thing is that the diagonals (dashed lines) meet in the middle at a right angle. This one, the sides are definitely not the same length. The SquareĪ square has equal sides (marked "s") and every angle is a right angle (90°)Ī square also fits the definition of a rectangle (all angles are 90°), and a rhombus (all sides are equal length). The little squares in each corner mean "right angle"Ī rectangle is a four-sided shape where every angle is a right angle (90°).Īlso opposite sides are parallel and of equal length. Let us look at each type in turn: The Rectangle Some types are also included in the definition of other types! For example a square, rhombus and rectangle are also parallelograms. Triangle V: It is obvious that this is a scalene triangle. Triangle P: Two out of the three sides of this triangle measure 7 ft. Triangle K: This is an equilateral triangle because all sides are congruent. There are special types of quadrilateral: Triangle M: Since at least two sides have the same equal measure, this triangle is an isosceles triangle. They should add to 360° Types of Quadrilaterals Try drawing a quadrilateral, and measure the angles.